Light deflecting method and apparatus efficiently using a floating mirror

ABSTRACT

Method of deflecting light includes the steps of providing a substrate and forming a supporting member on the substrate. Next forming step forms electrodes at predetermined positions on the substrate. Next forming step forms a plate-like-shaped thin film member including light reflecting means. Placing step places the plate-like-shaped thin film member on the supporting member so that an opposite surface thereof faces the electrodes. Forming step forms space regulating members on edges of the substrate for regulating a space formed above the substrate in which the plate-like-shaped thin film member is freely movable. Applying step applies predetermined voltages to the electrodes to change a tilt direction of the plate-like-shaped thin film member in accordance with the voltages applied to deflect the input light in an arbitrary direction. Disclosure also describes light deflecting apparatuses, light deflecting array apparatuses, image forming apparatuses, image projection display apparatuses, and optical data transmission apparatuses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/294,033, filed Nov. 14, 2002, U.S. Pat. No. 6,900,915 and is basedupon and claims the benefit of priority from the prior Japanese PatentApplication Nos. 2001-349415, filed Nov. 14, 2001, 2002-178216, filedJun. 19, 2002, and 2002-282858, filed Sep. 27, 2002, the entire contentsof each of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for lightdeflecting, and more particularly to a method and apparatus for lightdeflecting capable of efficiently moving a floating mirror with anelectrostatic attraction force.

2. Discussion of the Background

Conventionally, a light deflecting device and a light deflecting systemusing the light deflecting device are known, generating an electrostaticattraction force to bend a cantilever-like light reflecting member tochange a reflection direction relative to input light rays. Thisapparatus is described in Japanese Patent No. 2,941,952, Japanese PatentNo. 3,016871, Japanese Laid-Open Patent Application Publication No.10-510374, “Applied Physics Letters,” 1977, vol. 31, No. 8, pp521–pp523,by K. E. Petersen, and “Optics Letters,” vol. 7, No. 9, pp688–pp690 byD. M. Bloom.

Further, an image forming apparatus is also known, employing a lightdeflecting system in which a plurality of digital micro-mirror devicesare arranged in one or two dimensions. This apparatus is described inJapanese Laid-Open Patent Application Publication No. 06-138403.

In digital micro-mirror devices having a twisted-type light reflectionmember or a cantilever-like light reflecting member, a mirror portion istilted and has at least one fixed end. This device is described in areference of “Proc. SPIE,” 1989, vol. 1150, pp86–pp102.

However, in the light deflecting device and the digital micro-mirrordevice having the twisted-type light reflecting member or thecantilever-like light reflecting member, the light reflecting member isdifficult to be stably held and a response speed is late.

Also, in the above-mentioned digital micro-mirror device having thetwisted-type light reflecting member, a hinge of the twisted portion maydegrade its mechanical strength in a usage over an extended period oftime.

Further, a light deflecting device for switching light by driving adiffraction grating with an electrostatic attraction force limits anallowable wavelength of an input light ray.

In addition, Japanese Laid-Open Patent Application Publication No.2000-002842 describes a light deflecting device for performing a lightdeflection by causing a light reflecting member with both ends fixed todeform in a circular shape. This device requires a relatively highdriving voltage since the light reflecting member is fixed at both ends.

Further, Japanese Laid-Open Patent Application Publication No. 08-220455describes a mirror movable in two-axis directions and a displayapparatus using this mirror. In this mirror and apparatus, a mirrorplate made of a magnetic metal in a pan-like shape is fixed with aneedle pivot by a magnetic force to a mirror bed including a magnet, anda plurality of electrodes are formed on the mirror bed. When theelectrodes are applied with different voltages, a voltage difference isgenerated between the electrodes and the mirror plate by the action ofelectrostatic and the mirror plate is moved about the top of the needlepivot to come close to the electrodes. In this case, however, the mirrorplate is substantially fixed to the mirror base at the needle pivot withthe magnetic force. This structure is relatively complex and the mirrorplate is actually not held in a completely free condition.

Due to this structure, in which the mirror plate is made of a magneticmetal, the magnet is arranged under the mirror bed, and magnetic yokesare arranged around the mirror bed, it is very difficult to make thetwo-axis-movable mirror and the apparatus using the mirror through amicromachining process. In addition, the two-axis movable mirror and theapparatus using the mirror may emit magnetic force and the environmentsfor these apparatuses may be limited.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide a novel method of light deflecting which reduces a mechanicalstress and performs a superior light deflection.

Another object of the present invention is to provide a novel lightdeflecting apparatus which reduces a mechanical stress and performs asuperior light deflection.

Another object of the present invention is to provide a novel lightdeflecting array apparatus including a plurality of light deflectingapparatuses, each of which reduces a mechanical stress and performs asuperior light deflection.

Another object of the present invention is to provide a novel imageforming apparatus including a latent image forming mechanism using alight deflecting array apparatus which reduces a mechanical stress andperforms a superior light deflection.

Another object of the present invention is to provide a novel imageprojection display apparatus projecting an image on an image screenusing a light deflecting array apparatus which reduces a mechanicalstress and performs a superior light deflection.

Another object of the present invention is to provide a novel opticaldata transmission apparatus including a light switching mechanism usinga light deflecting array apparatus which reduces a mechanical stress andperforms a superior light deflection.

To achieve these and other objects, in one example, the presentinvention provides a novel method of deflecting input light indirections for at least one deflection-axis, which includes thefollowing seven steps. A providing step provides a substrate. A formingstep forms a supporting member on a surface of the substrate. A nextforming step forms a plurality of electrodes at predetermined positionsaround the supporting member on the surface of the substratecorresponding to the directions for at least one deflection-axis. A nextforming step forms a plate-like-shaped thin film member including lightreflecting means disposed on a surface of the plate-like-shaped thinfilm member for reflecting input light. A placing step places theplate-like-shaped thin film member on the supporting member so thatanother surface of the plate-like-shaped thin film member opposite tothe surface having the light reflecting means faces the plurality ofelectrodes. A forming step forms a plurality of space regulating memberson edges of the surface of the substrate for regulating a space formedabove the surface of the substrate in which the plate-like-shaped thinfilm member placed on the supporting member is freely movable. Aapplying step applies predetermined voltages to the plurality ofelectrodes to change a tilt direction of the plate-like-shaped thin filmmember in accordance with the voltages applied so as to deflect theinput light in an arbitrary direction out of the directions for at leastone deflection-axis.

The predetermined voltages may include at least one different voltage.

In the forming step of forming the supporting member, the supportingmember may be formed on the surface of the substrate such that a centerof gravity of the supporting member is on a normal to a center of thesurface of the substrate.

In the forming step of forming the supporting member, the supportingmember may be formed to have at least one slope connecting between a topportion and a bottom edge of the supporting member.

When the applying step applies the predetermined voltages to theplurality of electrodes, the plate-like-shaped thin film member may tiltin accordance with the voltages applied to come in contact with the atleast one slope of the supporting member so as to deflect the inputlight in the arbitrary direction out of the directions for at least onedeflection-axis.

To achieve the above-mentioned object, the present invention alsoprovides a novel light deflecting apparatus deflecting input light indirections for at least one deflection-axis. In one example, a novellight deflecting apparatus includes a substrate, a supporting member, aplurality of electrodes, a plate-like-shaped member, a light reflectingmember, and a plurality of space regulating member. The supportingmember is formed on a surface of the substrate. The plurality ofelectrodes are arranged at predetermined positions around the supportingmember on the surface of the substrate corresponding to the directionsfor at least one deflection-axis. The plate-like-shaped thin film memberis placed on the supporting member so that a bottom surface of theplate-like-shaped thin film member faces the plurality of electrodes.The light reflecting member is fixed to a surface of theplate-like-shaped thin film member opposite to the bottom surfacethereof, for reflecting the input light. The plurality of spaceregulating members are disposed on edges of the surface of the substratefor regulating a space formed above the surface of the substrate inwhich the plate-like-shaped thin film member placed on the supportingmember is freely movable to deflect the input light in an arbitrarydirection out of the directions for at least one deflection-axis.

One of the light reflecting member and the plate-like-shaped thin filmmember may include a conductive region facing the plurality ofelectrodes.

The supporting member may have at least one slope connecting between atop portion and a bottom edge thereof and the plate-like-shaped thinfilm member comes in contact with the at least one slope of thesupporting member.

A number of the plurality of space regulating members may correspond toa contour of the plate-like-shaped thin film member and the plurality ofspace regulating members are arranged with a predetermined pitch.

The plate-like-shaped thin film member may be in an electricallyfloating status.

The plurality of electrodes may be disposed to the at least one slope ofthe supporting member to face the plate-like-shaped member.

The plate-like-shaped member may determine a reflection directionrelative to the input light when tilting and coming in contact with thesubstrate by point.

The plate-like-shaped member may determine a reflection directionrelative to the input light when tilting and coming in contact with thesubstrate by line.

The present invention also provides novel light deflecting arrayapparatuses. The present invention also provides novel image formingapparatuses. The present invention also provides novel image projectiondisplay apparatuses. The present invention also provides novel opticaldata transmission apparatuses.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIGS. 1 and 2 are schematic diagrams for explaining a light deflectingapparatus according to an embodiment of the present invention;

FIGS. 3 and 4 are schematic diagrams for explaining a light reflectingfunction of a plate included in the light deflecting apparatus of FIG.1;

FIGS. 5–7 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 8–11 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 12–15 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 16–18 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 19–22 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 23 and 24 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 25 and 26 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 27–35 are schematic diagrams for explaining a principle of a lightdeflecting operation performed by the light deflecting apparatus of FIG.23;

FIGS. 36 and 37 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 38 and 39 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 40 and 41 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 42–44 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 45 and 46 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 47 and 48 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIG. 49 is a schematic diagrams of a one-dimension light deflectionarray including a plurality of the light deflecting apparatuses of FIG.1;

FIG. 50 is a schematic diagrams of a two-dimension light deflectionarray including a plurality of the light deflecting apparatuses of FIG.1;

FIGS. 51–61 are schematic diagrams for explaining a method of making thelight deflecting apparatus of FIG. 23 according to an embodiment of thepresent invention;

FIGS. 62–71 are schematic diagrams for explaining a method of making alight deflecting apparatus combining the light deflecting apparatuses ofFIGS. 6 and 23 according to an embodiment of the present invention;

FIGS. 72–80 are schematic diagrams for explaining a method of making thelight deflecting apparatus of FIG. 41 according to an embodiment of thepresent invention;

FIG. 81 is a schematic diagram for explaining an image forming apparatusincluding the light deflecting apparatus of FIG. 49;

FIG. 82 is a schematic diagram for explaining an image projectiondisplay apparatus including the light deflecting apparatus of FIG. 50;

FIG. 83 is a schematic diagram for explaining an optical datatransmission apparatus including the light deflecting apparatus of FIG.50;

FIGS. 84 and 85 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 86 and 87 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIG. 88 is a schematic diagram of a light deflecting apparatus accordingto another embodiment of the present invention;

FIGS. 89 and 90 are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 91A and 91B are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 92A and 92B are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 93A and 93B are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 94A and 94B are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 95A–95C are illustrations showing different shapes of supportingmember;

FIGS. 96A and 96B are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 97A and 97B are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 98A–98K are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention, with anexplanation of an operation principle;

FIG. 99 is a schematic diagram for explaining a principle of anelectrostatic attraction force;

FIGS. 100A–100M are schematic diagrams of a light deflecting apparatusaccording to another embodiment of the present invention, with anexplanation of an operation principle;

FIG. 101 is a schematic diagram of a light deflecting apparatusaccording to another embodiment of the present invention;

FIGS. 102A and 102B are schematic diagrams of a light deflecting arrayapparatus according to an embodiment of the present invention;

FIG. 103 is a schematic diagram of an image projection display apparatusaccording to an embodiment of the present invention;

FIG. 104 is a schematic diagram of an image forming apparatus accordingto an embodiment of the present invention;

FIGS. 105A and 105B are schematic diagrams of optical data transmissionapparatuses according to embodiments of the present invention;

FIGS. 106A–106H are schematic diagrams for explaining a method of makingthe light deflecting apparatus of FIG. 98A;

FIGS. 107A–107I are schematic diagrams for explaining a method of makingthe light deflecting apparatus of FIG. 97A;

FIGS. 108A–108D and 109A–109C are schematic diagrams showing differentshapes of supporting member;

FIGS. 110A and 110B are schematic diagrams of a light deflectingapparatus according to another embodiment of the present invention;

FIGS. 111A and 111B are schematic diagrams of a light deflectingapparatus according to another embodiment of the present invention;

FIG. 112 is a schematic diagrams of a light deflecting array apparatusaccording to another embodiment of the present invention;

FIGS. 113A, 113B, and 114 are schematic diagrams showing differentshapes of an angle bracket;

FIGS. 115A, 115B, 116, and 117 are schematic diagrams showing furtherdifferent shapes of an angle bracket; and

FIGS. 118–127 are schematic diagrams for explaining a method of making alight deflecting apparatus modified based on the light deflectingapparatus of FIG. 98A.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In describing preferred embodiments illustrated in the drawings,specific terminology is employed for the sake of clarity. However, thedisclosure of this patent specification is not intended to be limited tothe specific terminology so selected and it is to be understood thateach specific element includes all technical equivalents that operate ina similar manner. Referring now to the drawings, wherein like referencenumerals designate identical or corresponding parts throughout theseveral views, particularly to FIGS. 1, a description is made for alight deflecting apparatus 10 according to a preferred embodiment of thepresent invention. FIG. 1 is a plane view of the light deflectingapparatus 10, and FIG. 2 is a cross-section view taken on line A—A ofFIG. 1. The light deflecting apparatus 10 deflects input light into asignal axial reflective direction or two axial reflective directions. Asshown in FIGS. 1 and 2, the light deflecting apparatus 10 includes areflecting member 1, a plate-like-shaped member 2, a substrate 3, asupporting member 4, four pieces of angle brackets 5, and an electrode6.

The reflecting member 1 is in a thin film shape and includes areflecting surface la for efficiently reflecting input light. Thereflecting member 1 is attached onto the plate-like-shaped member 2which is hereinafter referred to simply as a plate 2. The plate 2 is ina thin film shape and has a surface onto which the reflecting member 1is fixed. The substrate 3 is made of silicon, for example, and has asurface on which the supporting member 4 is formed. The plate 2 isplaced on the supporting member 4 without being fixed to any one of thesubstrate 3, supporting member 4, and the angle brackets 5. The anglebrackets 5 regulate a space for the plate 2 to move and are respectivelyreferred to as angle brackets 5 a ₁, 5 a ₂, 5 a ₃, and 5 a ₄ inassociation with their positions, as shown in FIG. 1, for conveniencesake. In some cases, the angle brackets 5 may also be referred to asspace regulating members 5. The supporting member 4 is formed on thesubstrate 3 such that a center of gravity of the supporting member is ona normal to a center of an upper surface of the substrate 3. Thesupporting member 4 serves as a fulcrum for the movement of the plate 2.Thereby, the plate 2 placed thereon is freely movable about the toppoint of the supporting member 4 within a free space G determined by theangle brackets 5 a ₁–5 a ₄ and the upper surface of the substrate 3. Theelectrode 6 is formed on the upper surface of the substrate 3 tosurround the supporting member 4 and to face the back surface of theplate 2.

Since the plate 2 is formed in a thin film shape and therefore has arelatively light weight, an impact to the plate 2 caused by contactingthe angle brackets 5 a ₁–5 a ₄ during standby or the substrate 3 underoperating conditions may negligibly be small. This allows the lightdeflecting apparatus 10 to have a stable mechanical strength for a usageover an extended period of time with lesser variations or degradation inthe mechanism.

The substrate 3 is preferably, in consideration of miniaturization, amaterial generally for use in a semiconductor process or a liquidcrystal process, such as silicon, glass, or the like.

Further, the substrate 3 may be combined with a driving circuitsubstrate (not shown) having a plane direction (100) to make the lightdeflecting apparatus 10 in a simple and lower cost structure.

The angle brackets 5 a ₁–5 a ₄ have an angled top portion for stoppingthe plate 2 and, as described above, regulate the free space G formed bythe back surface of the plate 2 and the upper surface of the substrate 3to limit the movement of the plate 2 within the free space G. In thelight deflecting apparatus 10, the numbers and the positions of theangle brackets 5 a ₁–5 a ₄ correspond to the shape of the plate 2, whichis in a substantially square form having four corners, to cover theentire plate 2. In other cases, the numbers and positions of the anglebracket members 5 a ₁–5 a ₄ may be different to cover the entire plate 2when the plate 2 has a different shape with a different number ofcorners.

The angle brackets 5 a ₁–5 a ₄ are made of a silicon oxide film or achromic oxide film, for example. Because of this thin film structure,when a one-dimensional light deflecting array (not shown) or atwo-dimensional light deflecting array (not shown) is formed with aplurality of the light deflecting apparatuses 10, for example, a totalreflecting area of the reflecting surfaces la of the reflecting members1 can substantially be maximized. In addition, such an array can be madein a space saving fashion while having a relatively high mechanicalstrength.

The supporting member 4 serving as the fulcrum for the movement of theplate 2 may be formed in various shapes according to performancesrequired to the light defecting apparatus 10, as described later. Thesupporting member 4 is made of a silicon oxide film or a silicon nitridefilm, for example, and therefore has a relatively high mechanicalstrength. As an alternative, the supporting member 4 may be made of aconductive material such as a metal film of various kinds to apply apotential to the plate 2 therethrough.

Referring to FIGS. 3 and 4, a light reflection of the light deflectingapparatus 10 is explained. FIGS. 3 and 4 diagrammatize manners of lightreflection by the light deflecting apparatus 10 when the reflectingsurface 1 a of the reflecting member 1 is plane and convex,respectively, for example.

As shown in FIG. 3, when the reflecting surface 1 a is plane, light raysentering the light reflection area of the light reflecting surface 1 aare reflected in one direction, i.e., in an-intended direction, withoutcausing a dispersion of the light rays in reflection. This featureavoids an adverse effect to adjacent optical devices and is thereforeimportant in particular when the light deflecting apparatus 10 isemployed in optical equipment such as an optical information processingapparatus, an image forming apparatus (e.g., an image forming apparatus200 explained later with reference to FIG. 81), an image projectiondisplay apparatus (e.g., an image projection display apparatus 300explained later with reference to FIG. 82), an optical transmissionapparatus (e.g., an optical data transmission apparatus 400 explainedlater with reference to FIG. 83), and so forth.

As for planeness of the reflecting surface 1 a of the reflecting member1, a radius of curvature with respect to the reflecting surface 1 a isrequired to be a few meters or greater.

When the reflecting surface la is convex, light rays entering the lightreflection area of the reflecting surface 1 a are reflected anddispersed in various directions, as shown in FIG. 4, causing an adverseeffect to adjacent optical devices. This adverse effect becomes severelyproblematic particularly in optical equipment such as an image formingapparatus (e.g., the image forming apparatus 200 explained later withreference to FIG. 81), an image projection display apparatus (e.g., theimage projection display apparatus 300 explained later with reference toFIG. 82), and so forth in which the reflected light rays are processedto perform an optical recording or displaying by an optical scalingsystem.

Referring to FIGS. 5–7, a light deflecting apparatus 10 a according toanother preferred embodiment of the present invention is explained. FIG.5 is a plane view of the light deflecting apparatus 10 a, and FIG. 6 isa cross-section view of the light deflecting apparatus 10 a taken online B—B of FIG. 5. The light deflecting apparatus 10 a of FIG. 5 is anapparatus modified on the basis of the light deflecting apparatus 10 ofFIG. 1, that is, the plate 2 is modified to a plate 2 a having arelatively small convex portion 2 a ₁ at substantially a centralposition thereof in contact with the supporting member 4.

With the above-mentioned convex portion 2 a ₁ arranged at the positionin contact with the supporting member 4, the plate 2 a is movable aboutthis convex portion 2 a ₁ without causing displacement in a surfacedirection when moving due to an electrostatic attraction, for example.That is, the convex portion 2 a ₁ is determined by itself as the centerof the movement with respect to the plate 2 a.

With this feature, the plate 2 a is prevented from contacting verticalsurfaces of the angle brackets 5 a ₁–5 a ₄ when moving in the free spaceG, as shown in FIG. 6.

When the plate 2 a does not have the convex portion 2 a ₁, as shown inFIG. 7, the plate 2 a may displace in a direction indicated by an arrowC1 and therefore the reflection performance of the light deflectingapparatus 10 a is degraded. Moreover, this displacement may accelerate amechanical wearing of the plate 2 a and the supporting member 4,resulting in weakening the mechanical strength.

Referring to FIGS. 8–11, a light deflecting apparatus 10 b according toanother preferred embodiment of the present invention is explained. FIG.8 is a plane view of the light deflecting apparatus 10 b, and FIG. 9 isa cross-section view of the light deflecting apparatus 10 b taken online D—D of FIG. 8. The light deflecting apparatus 10 b of FIG. 8 is anapparatus modified on the basis of the light deflecting apparatus 10 ofFIG. 1, that is, the supporting member 4 is modified to a supportingmember 4 b having a cylindrical cross section 4 b ₁ and a circular topsurface 4 b ₂, as shown in FIG. 10. Accordingly, the plate 2 issupported directly by the circular top surface 4 b ₂ of the supportingmember 4 b. The supporting member 4 b is made of a silicon oxide film ora silicon nitride film, for example, and therefore it may have arelatively high mechanical strength. As an alternative, the supportingmember 4 b may be made of a conductive material such as a metal film ofvarious kinds to apply a potential to the plate 2 therethrough.

As shown in FIG. 11, the supporting member 4 b may have a taperedportion 4 b ₃ immediately adjacent to the circular top surface 4 b ₂ soas to reduce the area of the circular top surface 4 b ₂.

With the supporting member 4 b having the circular top surface 4 b ₂,the plate 2 carrying the reflecting member 1 thereon can easily betilted in an arbitrary direction corresponding to a direction in whichan electrostatic attraction acts. Further, the reduction of the area ofthe circular top surface 4 b 2 facilitates the light deflection in thetwo axial directions.

Referring to FIGS. 12–15, a light deflecting apparatus 10 c according toanother preferred embodiment of the present invention is explained. FIG.12 is a plane view of the light deflecting apparatus 10 c, and FIG. 13is a cross-section view of the light deflecting apparatus 10 c taken online E—E of FIG. 12. The light deflecting apparatus 10 c of FIG. 12 isan apparatus modified on the basis of the light deflecting apparatus 10of FIG. 1, that is, the supporting member 4 is modified to a supportingmember 4 c having a conical shape 4 c 1 and a pointed top 4 c ₂, asshown in FIG. 14. Accordingly, the plate 2 is supported directly by thepointed top 4 c ₂ of the supporting member 4 c. The supporting member 4c is made of a silicon oxide film or a silicon nitride film, forexample, and therefore has a relatively high mechanical strength. As analternative, the supporting member 4 c may be made of a conductivematerial such as a metal film of various kinds to apply a potential tothe plate 2 therethrough.

As shown in FIG. 15, the supporting member 4 c may have a rounded top 4c ₃ instead of the pointed top 4 c ₂.

With the supporting member 4 c having the conical shape 4 c 1, a bottomside of the supporting member 4 c contacting the substrate 3 has arelatively high mechanical strength. In addition, by reducing a contactarea between the plate 2 and the supporting member 4 c, the plate 2 maybe prevented from attaching to the surface of the substrate 3 orreceiving a charge from the substrate 3. This is because the plate 2 hasone end, e.g., an end 2 c, contacting an upper surface of the substrate3 by which the movement of the plate 2 is regulated. Further, because ofthis structure that the supporting member 4 c has the pointed top 4 c ₂and supports the plate 2 with it, the plate 2 can easily be tilted in anarbitrary direction corresponding to a direction in which anelectrostatic attraction acts.

Referring to FIGS. 16 and 17, a light deflecting apparatus 10 daccording to another preferred embodiment of the present invention isexplained. FIG. 16 is a plane view of the light deflecting apparatus 10d, and FIG. 17 is a cross-section view of the light deflecting apparatus10 d taken on line F—F of FIG. 16. The light deflecting apparatus 10 dof FIG. 16 is an apparatus modified on the basis of the light deflectingapparatus 10 of FIG. 1, that is, the supporting member 4 is modified toa supporting member 4 d having a rectangular solid shape 4 d ₁ and arectangular surface 4 d ₂, as shown in FIG. 18. Accordingly, the plate 2is supported directly by the rectangular surface 4 d ₂ of the supportingmember 4 d. The supporting member 4 d is made of a silicon oxide film ora silicon nitride film, for example, and therefore has a relatively highmechanical strength. As an alternative, the supporting member 4 d may bemade of a conductive material such as a metal film of various kinds toapply a potential to the plate 2 therethrough.

Because of this structure in that the supporting member 4 d having therectangular surface 4 d ₂, the plate 2 can easily be tilted in adirection parallel to the rectangular surface 4 d ₂. That is, the plate2 can easily be tilted in a one-axial direction according to anelectrostatic attraction in a stable manner.

Referring to FIGS. 19–22, a light deflecting apparatus 10 e according toanother preferred embodiment of the present invention is explained. FIG.19 is a plane view of the light deflecting apparatus 10 e, and FIG. 20is a cross-section view of the light deflecting apparatus 10 e taken online G—G of FIG. 19. The light deflecting apparatus 10 e of FIG. 19 isan apparatus modified on the basis of the light deflecting apparatus 10of FIG. 1, that is, the supporting member 4 is modified to a supportingmember 4 e having a prism shape 4 e ₁ and an edged ridgeline 4 e ₂, asshown in FIG. 21. Accordingly, the plate 2 is supported directly by theedged ridgeline 4 e ₂ of the supporting member 4 e. The supportingmember 4 e is made of a silicon oxide film or a silicon nitride film,for example, and therefore has a relatively high mechanical strength. Asan alternative, the supporting member 4 e may be made of a conductivematerial such as a metal film of various kinds to apply a potential tothe plate 2 therethrough.

As shown in FIG. 22, the supporting member 4 e may have a roundedridgeline 4 e 3 instead of the edged ridgeline 4 e ₂.

With the supporting member 4 e having the prism shape 4 e ₁, a bottomside of the supporting member 4 e contacting the substrate 3 has arelatively high mechanical strength. In addition, by reducing a contactarea between the plate 2 and the supporting member 4 e, the plate 2 mayeffectively be prevented from attaching to the surface of the substrate3 or receiving a charge from the substrate 3. This is because the plate2 has one end, e.g., an end 2 e, contacting an upper surface of thesubstrate 3 by which the movement of the plate 2 is regulated. Further,because of this structure that the supporting member 4 e has the edgedridgeline 4 e ₁ and supports the plate 2 with it, a contacting portionbetween the plate 2 and the supporting member 4 e is relatively smalland therefore the plate 2 can easily be tilted according to anelectrostatic attraction in a one-axial direction in a stable manner.

Referring to FIGS. 23 and 24, a light deflecting apparatus 10 faccording to another preferred embodiment of the present invention isexplained. FIG. 23 is a plane view of the light deflecting apparatus 10f, and FIG. 24 is a cross-section view of the light deflecting apparatus10 f taken on line H—H of FIG. 23. The light deflecting apparatus 10 fof FIG. 23 is an apparatus modified on the basis of the light deflectingapparatus 10 c of FIG. 12, that is, the electrode 6 is divided into fourelectrodes 6 f ₁–6 f ₄, as shown in FIG. 23. In the light deflectingapparatus 10 f of FIG. 23, the electrodes 6 f ₁–6 f ₄ are formed on thesubstrate 3 in a symmetrical arrangement relative to the supportingmember 4 c which supports the electrically floating plate 2. Theelectrodes 6 f ₁–6 f ₄ are preferably made of metal such as aluminummetal, titan nitride, or titan, for example, to have a superiorconductivity.

With this structure, when the electrodes 6 f ₁–6 f ₄ are provided withdifferent potentials, such differences in potentials among theelectrodes 6 f ₁–6 f ₄ will cause an electrostatic attraction forcewhich acts between the plate 2 and the electrodes 6 f ₁–6 f ₄, resultingin a movement of the plate 2 in an arbitrary direction.

In addition, the plate 2 settled in one direction can quickly be movedand settled in another arbitrary direction by changing the respectivepotentials of the electrodes 6 f ₁–6 f ₄.

Although the electrode 6 is divided into the electrodes 6 f ₁–6 f ₄, asdescribed above, the division of the electrode 6 is not limited to thatand the electrode 6 may preferably be divided into at least two pieces.

Further, with this structure, potential differences can arbitrarily begenerated among the electrodes 6 f ₁–6 f ₄ so as to control the tilt ofthe plate 2 in two axial directions in a precise manner. Thereby, thelight deflecting apparatus 10 f can stably perform the light deflectingin a quick and responsive manner with relatively simple structure andcontrol.

Referring to FIGS. 25 and 26, a light deflecting apparatus 10 gaccording to another preferred embodiment of the present invention isexplained. FIG. 25 is a plane view of the light deflecting apparatus 10g, and FIG. 26 is a cross-section view of the light deflecting apparatus10 g taken on line I—I of FIG. 25. The light deflecting apparatus 10 gof FIG. 25 is an apparatus modified on the basis of the light deflectingapparatus 10 f of FIG. 23, that is, the reflecting surface 1 a of thereflecting member 1 or at least a part of the plate 2 includes aconductive area 2 g in the light reflecting area thereof such that atleast a part of the conductive area 2 g faces the electrodes 6 f ₁ –6 f₄. The conductive area 2 g preferably is made of metal such as aluminummetal, titan nitride, or titan, for example, to have a superiorconductivity. When the plate 2 combines the light reflecting area of thereflecting surface 1 a of the reflecting member 1 to reduce the cost,the plate 2 preferably has an upper surface made of aluminum metal, inparticular, for a superior light reflecting nature.

With this structure, an electrostatic attraction force acting betweenthe plate 2 and the electrodes 6 f ₁–6 f ₄ can be generated by anapplication of relatively low driving voltages to the electrodes 6 f ₁–6f ₄, thereby moving the plate 2 in an arbitrary direction.

In addition, the plate 2 settled in one direction can quickly be movedand settled in another arbitrary direction by changing the respectivepotentials of the electrodes 6 f 1–6 f 4.

Further, with this structure, potential differences can arbitrarily begenerated among the electrodes 6 f ₁–6 f ₄ so as to control the tilt ofthe plate 2 in two axial directions in a precise manner.

Next, operations of the light deflecting apparatus 10 f shown in FIG. 23are explained with reference to FIGS. 27–34. In FIG. 27, the view of thelight deflecting apparatus 10 f is provided with cross section linesJ—J, K—K, and L—L which are used in the detailed discussion below. Asindicated in a cross section view of FIG. 28, taken on line J—J of FIG.27, the light deflecting apparatus 10 f is in a floating status, havingno portion thereof contacting neither the substrate 3 or the supportingmember 44. The view of FIG. 28 is virtually made, for the sake ofclarity, to demonstrate a condition when the light deflecting apparatus10 f is in an initial status, in consideration of the nature that theplate 2 is freely movable in the free space G.

FIGS. 29 and 30 are cross section views taken on lines J—J and K—K,respectively, demonstrating a reset operation of the light deflectingapparatus 10 f. When the light deflecting apparatus 10 f settled in theinitial status performs the reset operation, the plate 2 is moved fromthe position in the initial status of FIG. 28 to a reset position, asshown in FIGS. 29 and 30. In the reset position, the plate 2 issupported by the supporting member 4 c at a central position of theplate 2 and has at least one edge portion, e.g., an edge portion 2 fshown in FIG. 29, contacting the substrate 3.

In the reset operation, the electrodes 6 f ₁–6 f ₄ are applied with thefollowing exemplary voltages:

6 f ₁; X volts,

6 f ₂; 0 volts,

6 f ₃; X/2 volts, and

6 f ₄; X/2 volts.

With the application of these voltages, an electrostatic attractionforce is generated between the plate 2 and the electrodes 6 f ₁–6 f ₄ ina direction indicated by arrows C2 and C3, as shown in FIG. 29. Thearrows C2 and C3 indicate not only directions but also magnitudes of theelectrostatic attraction force by size of arrows, as the electrostaticattraction force varies depending upon a position of the plate 2.Accordingly, the arrows C2 and C3 in FIG. 29 indicate that magnitudes ofthe electrostatic attraction force acting between the plate 2 and thesubstrate 3 are uneven and therefore the plate 2 is tilted in adirection of arrow C4 due to this unevenness of the force. FIG. 30 showsthis tilting movement from a 90-degree different angle which is the viewtaken on line K—K. In FIG. 30, as arrows C5 indicates, the electrostaticattraction force evenly acts between the plate 2 and the substrate 3,and therefore the movement of the plate 2 is not seen in the view ofFIG. 30.

From the views of FIGS. 29 and 30, it is understand that the plate 2 istilted about a first axis on line K—K. Thus, the angle of the plate 2 ischanged and the light reflecting area in the light reflecting portion 1b of the light reflecting member 1 changes its light reflecting angle ina desired direction. This desired direction is referred to as a resetdirection and, when the plate 2 is tilted in the reset direction, thelight deflecting apparatus 10 f is said to be in a reset status.

The voltage X is determined according to various factors includingdistances between the plate 2 and each of the electrodes 6 f ₁–6 f ₄ andcapacitances of the plate 2 and the electrodes 6 f ₁–6 f ₄, for example.This voltage X required in the reset operation is slightly greater thana voltage Y required in a regular tilting operation in which the plate 2supported by the supporting member 4 c is tilted.

In the subsequent drawings including FIGS. 31–35, arrows for indicatingdirections and magnitudes of the electrostatic attraction force are notgiven reference labels such as the arrows C2 and C3 or the arrow C5, forexample, since the purpose of these arrows is clear.

FIGS. 31 and 32 are cross section views of the light deflectingapparatus 10 f, taken on lines J—J and K—K, respectively, demonstratinga first operation of the light deflecting apparatus 10 f. When the lightdeflecting apparatus 10 f settled in the reset status shown in FIGS. 29and 30 performs the first operation, the plate 2 is tilted in adirection of an arrow C6, as shown in FIG. 31, and changes its positionfrom the position in the reset status of FIGS. 29 and 30 to a firstposition shown in FIGS. 31 and 32. The direction of the arrow C6 of FIG.31 is a reverse direction relative to the direction of the arrow C4 ofFIG. 29, and this tilting movement of the plate 2 shown in FIGS. 31 and32 is made about the same first axis on line K—K, as in the case shownin FIGS. 29 and 30. The position to which the plate 2 moves through thefirst operation is referred to as a first position. In the firstposition, the plate 2 is supported by the supporting member 4 c at thecentral position of the plate 2 and has at least one edge portion (e.g.,the portion 2 f) contacting the substrate 3.

Thus, the light deflecting apparatus 10 f can change the direction ofthe light deflection with the first axis.

In the first operation, the electrodes 6 f ₁–6 f ₄ are applied with thefollowing exemplary voltages:

6 f ₁; Y/2 volts,

6 f ₂; Y/2 volts,

6 f ₃; Y volt, and

6 f ₄; 0 volts.

FIGS. 33 and 34 are cross section views of the light deflectingapparatus 10 f, taken on lines J—J and K—K, respectively, demonstratinga second operation of the light deflecting apparatus 10 f. When thelight deflecting apparatus 10 f settled in the reset status shown inFIGS. 29 and 30 performs the second operation, the plate 2 is tilted ina direction of an arrow C7, as shown in FIG. 34, and changes itsposition from the position in the reset status of FIGS. 29 and 30 to asecond position shown in FIGS. 33 and 34. In this case, the tiltingmovement of the plate 2 shown in FIGS. 33 and 34 is made about a secondaxis on line J—J. The position to which the plate 2 moves through thesecond operation is referred to as a second position. In the secondposition, the plate 2 is supported by the supporting member 4 c at thecentral position of the plate 2 and has at least one edge portion (e.g.,the portion 2 f) contacting the substrate 3.

Thus, the light deflecting apparatus 10 f can change the direction ofthe light deflection with the second axis.

In the second operation, the electrodes 6 f ₁–6 f ₄ are applied with thefollowing exemplary voltages:

6 f ₁; Y/2 volts,

6 f ₂; 0 volts,

6 f ₃; Y/2 volts, and

6 f ₄; Y volt.

As described above, the light deflecting apparatus 10 f can change thedirection of the light deflection with the first and second axes by thefirst and second operations applying the above-described predeterminedvoltages to the electrodes 6 f ₁–6 f ₄.

With reference to FIG. 35, the principle of the electrostatic attractionis explained. FIG. 35 is a cross section view of the light deflectingapparatus 10 f, for example, taken on line L—L of FIG. 27. In FIG. 35,the light deflecting apparatus 10 f is in the reset operation, applyinga positive voltage of X volts to the electrode 6 f ₁ and a voltage of 0volts to 6 f ₂.

Initially, the plate 2 is electrically floated. When the positivevoltage is applied to the electrode 6 f ₁, the electrode 6 f ₁ will havepositive charges and consequently negative charges appear in a portionof the plate 2 facing the electrode 6 f ₁ in a dielectric manner via thefree space G. At this time, if the plate 2 has a conductive area, thenegative charges are effectively dispersed in the plate 2 through theconductive area. Thereby, an electrostatic attraction force is generatedbetween the electrode 6 f ₁ and the corresponding portion of the plate2.

On the other hand, the generation of the negative charges in the plate 2cause a generation of positive charges in a portion of the plate 2facing the electrode 6 f ₂ and the generated positive charges willspread in the plate 2 through the conductive area. Then, in response tothe positive charges, negative charges appear on the electrode 6 f ₂.Therefore, an electrostatic attraction force is also generated betweenthe electrode 6 f ₂ and the corresponding portion of the plate 2.

In this way, the electrostatic attraction is generated between the plate2 and the electrodes 6 f ₁ and 6 f ₂, for example.

The above-described steps in the generation of the electrostaticattraction actually proceed substantially in a simultaneous fashion inresponse to the voltage difference between the electrodes 6 f ₁ and 6 f₂.

In addition, the electrically floating plate 2 including the conductivearea has a certain voltage determined between the voltages of theelectrodes 6 f ₁ and 6 f ₂. Accordingly, the voltage difference betweenthe certain voltage and the voltage of the electrode 6 f ₁ generates theelectrostatic attraction and also the voltage difference between thecertain voltage and the voltage of the electrode 6 f ₂ generates theelectrostatic attraction. This certain voltage may vary mainly accordingto structural factors including areas of the free space G and theelectrodes 6 f ₁ and 6 f ₂, for example.

Referring to FIGS. 36 and 37, a light deflecting apparatus 10 haccording to another preferred embodiment of the present invention isexplained. FIG. 36 is a plane view of the light deflecting apparatus 10h, and FIG. 37 is a cross-section view of the light deflecting apparatus10 h taken on line P—P of FIG. 36. The light deflecting apparatus 10 hof FIG. 36 is an apparatus modified on the basis of the light deflectingapparatus 10 f of FIG. 23, that is, the supporting member 4 c ismodified to a supporting member 4 h. The supporting member 4 h has arelative large prism-like shape with a bottom surface having an areanearly covering an entire area of the upper surface of the substance 3,and the electrodes 6 f ₁–6 f ₄ are disposed on roof-like slopes of thesupporting member 4 h, as shown in FIGS. 36 and 37.

Although the light deflecting apparatus 10 h has the four dividedelectrodes (i.e., the electrodes 6 f ₁–6 f ₄), the division number withrespect to the electrode may not be limited to it and the electrode maybe divided into other number of pieces such as two, for example.

The supporting member 4 h is made of a silicon oxide film or a siliconnitride film, for example, and therefore has a relatively highmechanical strength.

As demonstrated in FIG. 37, with this structure, the electrode comescloser to the plate 2 as the position of the electrode is nearer to thesupporting point of the supporting member 4 h. This enables the lightdeflecting apparatus 10 h to generate a larger electrostatic attractionforce than that generated by the light deflecting apparatus 10 f of FIG.23, for example. In other words, the light deflecting apparatus 10 h canmove the plate 2 with a lower voltage than that needed by the lightdeflecting apparatus 10 f of FIG. 23.

Further, when the plate 2 is settled in one operational position, it iscaused to touch the entire surfaces of the corresponding electrodes.This may diffuse the impact in contact and therefore the mechanicalstrength may not be degraded through a usage for an extended period oftime. Also, moving the plate 2 with touching the entire surface of thecorresponding electrodes facilitates a directional control relative tothe plate 2. As a consequence, the operation is performed in a morestable manner and its response time becomes faster.

Referring to FIGS. 38 and 39, a light deflecting apparatus 10 iaccording to another preferred embodiment of the present invention isexplained. FIG. 38 is a plane view of the light deflecting apparatus 10i, and FIG. 39 is a cross-section view of the light deflecting apparatus10 i taken on line Q—Q of FIG. 38. The light deflecting apparatus 10 iof FIG. 38 is an apparatus modified on the basis of the light deflectingapparatus 10 h of FIG. 36, that is, the reflecting surface 1 a of thereflecting member 1 or at least a part of the plate 2 includes aconductive area 2 i in the light reflecting area thereof such that atleast a part of the conductive area 2 i faces the electrodes 6 f ₁–6 f₄. The conductive area 2 i preferably is made of metal such as aluminummetal, titan nitride, or titan, for example, in consideration ofconductivity.

With this structure, an electrostatic attraction force acting betweenthe plate 2 and the electrodes 6 f ₁–6 f ₄ can be generated by anapplication of relatively low driving voltages to the electrodes 6 f ₁–6f ₄, thereby moving the plate 2 in an arbitrary direction.

In addition, the plate 2 settled in one direction can quickly be movedand settled in another arbitrary direction by changing the respectivepotentials of the electrodes 6 f ₁–6 f ₄.

Further, with this structure, potential differences can arbitrarily begenerated among the electrodes 6 f ₁–6 f ₄ so as to control the tiltingmovement of the plate 2.

Referring to FIGS. 40 and 41, a light deflecting apparatus 10 jaccording to another preferred embodiment of the present invention isexplained. FIG. 40 is a plane view of the light deflecting apparatus 10j, and FIG. 41 is a cross-section view of the light deflecting apparatus10 j taken on line R—R of FIG. 41. The light deflecting apparatus 10 jof FIG. 40 is an apparatus modified on the basis of the light deflectingapparatus 10 h of FIG. 36, that is, the substrate 3 is modified to asubstrate 3 j to combine the supporting member 4 h therewith. Thesubstrate 3 j has hollows 3 j ₁ on the upper surface thereof to formroof-like slopes 3 j ₂ for serving as the supporting member 4 h of FIG.36. The electrodes 6 f ₁–6 f ₄ are disposed on the roof-like slopes 3 j₂. The angle bracket members 5 a ₁–5 a ₄ are disposed on the plane edgesurface of the substrate 3 j. The electrically floating plate 2 is heldby the supporting point of the substrate 3 j for free movement withinthe free space G limited by the top portions of the angle bracketmembers 5 a ₁–5 a ₄ and the electrodes 6 f ₁–6 f ₄. The supporting pointof the substrate 3 j is arranged below the plane edge surface of thesubstrate 3 j.

To form the hollows 3 j ₁, the upper surface of the substrate 3 j isetched, or, a relatively thick insulating layer 3 j ₃ is first formed onthe substrate 3 j, as shown in FIG. 41, and is then trimmed. During thiswork, the level of the supporting point is adjusted.

Since the hollows 3 j ₁ makes the free space G greater, it provides amargin for reducing the height of the angle bracket members 5 a ₁–5 a ₄.The angle bracket members 5 a ₁–5 a ₄ preferably have a high mechanicalstrength and therefore the reduction of the height of the angle bracketmembers 5 a ₁–5 a ₄ makes their mechanical strength higher.

With this structure, the height of the free space G can arbitrarilyadjusted so that the driving voltage for driving the circuit and thereset voltage can suitably adjusted.

Referring to FIGS. 42–44, a light deflecting apparatus 10 k according toanother preferred embodiment of the present invention is explained. FIG.42 is a plane view of the light deflecting apparatus 10 k, and FIG. 43is a cross-section view of the light deflecting apparatus 10 k taken online S—S of FIG. 42. The light deflecting apparatus 10 k of FIG. 42 isan apparatus modified on the basis of the light deflecting apparatus 10f of FIG. 23. In this modification, and the plate 2 and the reflectingmember 1 are modified to a plate 2 k and a reflecting member 1 k in acircular shape. In addition, the angle brackets 5 a ₁–5 a ₄ are modifiedto an angle bracket 5 k which is a circular single piece, and theelectrodes 6 f ₁–6 f ₄ are modified to electrodes 6 k ₁–6 k ₄ which havethe shapes shown in FIG. 42.

In the light deflecting apparatus 10 k having this structure, thereflected light reflected by the reflecting member 1 k become a lightray having a circular cross section. Accordingly, in an image formingapparatus (e.g., the image forming apparatus 200 explained later withreference to FIG. 81) or an image projection display apparatus (e.g.,the image projection display apparatus 300 explained later withreference to FIG. 83) employing the light deflecting apparatus 10 k, asingle pixel can be formed in a circular shape as shown in FIG. 44. Withthe plate 2 having an approximately square shape, a pixel is formed in arectangular shape and a space between adjacent two pixels becomes a lineshaped noise. However, the circular-shaped pixel produced with the lightdeflecting apparatus 10 k can reduce this noise and it can consequentlyform a relatively high precision image.

Referring to FIGS. 45–46, a light deflecting apparatus 10 m according toanother preferred embodiment of the present invention is explained. FIG.45 is a plane view of the light deflecting apparatus 10 m, and FIG. 46is a cross-section view of the light deflecting apparatus 10 m taken online T—T of FIG. 45. The light deflecting apparatus 10 m of FIG. 45 isan apparatus modified on the basis of the light deflecting apparatus 10of FIG. 1. In this modification, the angle brackets 5 a ₁–5 a ₄ arearranged at corners of a square of the substrate 3 having a side lengthm, as shown in FIG. 45.

With this structure, an etching work with respect to the substrate 3,explained later, is facilitated. In the etching process, the plate 2 andthe substrate 3 are immersed in an etching liquid and therefore amanufacturing yield is improved by shortening the etching time.

Referring to FIGS. 47–48, a light deflecting apparatus 10 n according toanother preferred embodiment of the present invention is explained. FIG.47 is a plane view of the light deflecting apparatus 10 n, and FIG. 48is a cross-section view of the light deflecting apparatus 10 n taken online U—U of FIG. 47. The light deflecting apparatus 10 n of FIG. 47 isan apparatus modified on the basis of the light deflecting apparatus 10of FIG. 1. In this modification, the angle brackets 5 a ₁–5 a ₄ arechanged to an angle bracket 5 n having a single-piececontinuous-wall-like shape, as shown in FIG. 47.

With this structure, the plate 2 is more strictly prevented from goingout of the free space G. As a result, the mechanical strength is lessdegraded through a usage for an extended period of time and thereforethe light deflecting apparatus 10 n can stably operate the lightdeflection over an extended period of time.

Since the upper movement of the plate 2 is restricted by the top angledportion of the bracket 5 n, the angle bracket 5 n is preferably made ofan insulating film to avoid a transfer of charges from the plate 2 tothe angle bracket 5 n when contacting. Thus, the plate 2 can maintainits electrically floating status.

The angle bracket 5 n is also preferably made of a translucent film(e.g., a silicon oxide film). When the angle bracket 5 n is made of anon-translucent material, the light entering the top angled portion ofthe angle bracket 5 n does not reach the reflecting surface 1 a of thereflecting member 1. With the angle bracket 5 n made of a translucentfilm, however, the light entering the top angled portion of the anglebracket 5 n passes through it and is reflected by the reflecting surface1 a. of the reflecting member 1. Thus, the effective light amount whichis often referred to as an “ON” light amount is increased. This allowsthe light deflecting apparatus ion to stably perform a fast responsivelight deflection operation.

The silicon oxide film has a superior insulation nature as well as thetranslucent nature and therefore making the angle bracket 5 n of asilicon oxide film facilitates a micromachining and a high integrationmachining of the light deflecting apparatus 10 n, which methods areexplained later. Thereby, it becomes possible to manufacture in arelatively low cost the light deflecting apparatus 10 n with the anglebracket 5 n made of the silicon oxide film which can stably perform afast responsive light deflection operation.

As an alternative, the angle bracket 5 n may be made of alight-resistant film (e.g., a chromic oxide film) to cut down a lightreflection in an undesired direction and, accordingly, a stray lightfrom the deflected light is prevented from entering into the light in adesired direction. Since the stray light is a light element generatedwhen a light deflection in a desired direction is not operated, theangle bracket 5 n made of a chromic oxide film, for example, restrictsan “OFF” light amount which represents a light amount when the lightdeflection in a desired direction is not operated. Therefore, the lightdeflecting apparatus 10 n having the angle bracket 5 n made of a chromicoxide film can stably perform the light deflection operation.

The chromic oxide film has a superior insulation nature as well as thelight-resistant nature and therefore it facilitates a micromachining anda high integration machining of the light deflecting apparatus 10 n,which methods are explained later. Thereby, it becomes possible tomanufacture in a relatively low cost the light deflecting apparatus 10 nwith the angle bracket 5 n made of the chromic oxide film which canstably perform a fast responsive light deflection operation.

Further, the plate 2 is preferably made of a silicon nitride film andthe light reflecting surface 1 a of the light reflecting member 1 ismade of an aluminum metal film which has high conductivity andreflectivity.

The plate 2 made of a silicon nitride film has a high dielectricbreakdown voltage and a high resistance against a fatigue failure or adegradation caused through a usage over an extended period of time.Accordingly, the plate 2 having a high insulation nature and a highmechanical strength is formed in a light-weighted thin shape by using asilicon nitride film. With the plate 2 formed in a light-weighted thinshape, a high speed operation for a relatively high frequency such as afrequency of at least a few tens of kilohertz, for example, can beachieved.

In addition, by making the reflecting surface 1 a of an aluminum metalfilm having natures of a high light reflectivity and a highconductivity, it becomes possible to combine a conductive area of theplate 2 with the reflecting surface 1 a. This allows the lightdeflecting apparatus 10 n to drive the plate 2 with a lower drivingvoltage and to output a higher reflection light amount.

FIG. 49 shows a light deflecting apparatus 20 which is a one-dimensionlight deflection array including a plurality of the above-describedlight deflecting apparatus 10, for example, arranged in a one-dimensionformation. In this structure, the light deflecting apparatus 10 may bereplaced with any one of the above-described light deflectingapparatuses 10 a–10 n. The light deflecting apparatus 20 can be employedin a latent image forming mechanism of an image forming apparatus (e.g.,the image forming apparatus 200 explained later with reference to FIG.81), for example.

FIG. 50 shows a light deflecting apparatus 30 which is a two-dimensionlight deflection array including a plurality of the one-dimension lightdeflecting arrays 10, for example, arranged in a two-dimensionformation. The light deflecting apparatus 30 can be employed in a lightswitching mechanism of an image projection display apparatus, forexample.

Referring to FIGS. 51–59, an exemplary method of making a lightdeflecting apparatus is explained. In this discussion, a lightdeflecting apparatus to be made is an apparatus similar to the lightdeflecting apparatus 10 f of FIG. 23, as an example. A first processprovides a silicon oxide film on the silicon substrate 3 with a plasmaCVD (chemical-vapor deposition) method. Then, a photography using aphotomask having a pattern with an area coverage modulation or aphotography which thermally deforms a resist pattern is used to form aresist pattern having an approximate shape and a thickness of thesupporting member 4 c. After that, the formed resist pattern is deformedto an exact shape of the supporting member 4 c with a dry etchingmethod, as shown in FIG. 51.

In the above process, the silicon oxide film having a thickness ofapproximately 2 μm may be formed, and the works for forming thesupporting member 4 c may be performed in an upper layer ofapproximately 1 μm.

The height of the top of the supporting-member 4 c is approximately 1μm.

A subsequent process provides the electrodes 6 f ₁–6 f ₄ made of atitanium nitride film. In this process, a titanium nitride film isformed to have a thickness of 0.01 μm with a DC magnetron sputteringprocess and is patterned into the electrodes 6 f ₁–6 f ₄ with aphotography and a dry etching method. In FIG. 52 (and also in thesubsequent drawings), the electrodes 6 f ₁–6 f ₄ are represented byreference numeral 6 for the convenience sake.

Then, a next process provides a protection layer 6 f ₅ made of a siliconnitride film having a thickness of 0.2 μm with the plasma CVD method.This protection layer 6 f ₅ is formed to protect the surfaces of theelectrodes 6 f ₁–6 f ₄ (see FIG. 53).

A next process forms a noncrystalline silicon film having a thickness of2 μm on the protection layer 6 f ₅ with a sputtering method, and thenoncrystalline silicon film is smoothed through a process time controlusing a CMP (chemical mechanical polishing) technology. In this example,the process time control is conducted with reference to a time period inthat the thickness of the noncrystalline silicon film remaining on thetop of the supporting member 4 c is reduced to 0.1 μm. Thenoncrystalline silicon film remaining on the protection layer 6 f ₅ isreferred to as a first sacrifice layer 7 (see FIG. 54).

As an alternative to the noncrystalline silicon film, the firstsacrifice layer 7 may be made of a polyimide film or a photosensitiveorganic film, or a resist film or a polycrystalline silicon film whichare generally used in a semiconductor process. The smoothing method maybe a reflow method with a thermal processing or an etch back method withthe dry etching.

Then, a next process forms a silicon nitride layer of a 0.2-μm thick onthe first sacrifice layer 7 with the plasma CVD method and subsequentlyforms an aluminum metal film of a 0.05-μm thick on the silicon nitridelayer with the sputtering method. After that, the aluminum metal film ispatterned into a conductive area of the plate 2 combining the reflectingsurface 1 a and the silicon nitride layer is patterned into the plate 2,with the photography and the dry etching method (see FIG. 55).

A next process provides a noncrystalline silicon film of a 1-μm thick onthe conductive area of the plate 2 with the sputtering method. Thisnoncrystalline silicon film is referred to as a second sacrifice layer 7a (see FIG. 56). The second sacrifice layer 7 a may made of a resistfilm or polycrystalline silicon film which are generally used in asemiconductor process.

A subsequent process divides each light deflecting apparatus withpatterns of the first and second sacrifice layers 7 and 7 a togetherusing the photography and the dry etching method. At this time, thepattern areas of the first and second sacrifice layers 7 and 7 a areslightly larger than the area of the plate 2 including the conductivearea combined with the reflecting surface 1 a of the reflecting member 1(see FIG. 57). This process prepares for a next process for providingthe angle brackets 5 around the plate 2.

FIG. 58 shows a process for forming the angle brackets 5 (i.e., theangel brackets 5 a ₁–5 a ₄). In this process, a silicon oxide film of a0.8-μm thick is formed with the plasma CVD method and is patterned tomake the angle brackets 5 with the photography and the dry etchingmethod.

Then, a final process removes the remaining first and second sacrificelayers 7 and 7 a through an opening with a wet etching method so thatthe plate 2 is supported by the supporting member 4 c for a freemovement within the free space G. Thus, the procedure for making thelight deflecting apparatus 10 f shown in FIG. 23 is completed (see FIG.59).

In this process, the angle brackets 5 are positioned at the four cornersof the first and second sacrifice layers 7 and 7 a in the substantiallysquare shape with leaving the four sides open and therefore the etchingremoval can be completed in a relatively short period of time.

In the process for forming the angle brackets 5 shown in FIG. 58, theangel brackets 5 may have other shapes as shown in FIGS. 60 and 61, forexample.

The thus-made light deflecting apparatus 10 f with the method explainedwith reference to FIGS. 51–59 is capable of stably performing afast-responsive light deflection in directions for one deflection-axisor two deflection-axes by a simple control with a simple structurewithout restricting an input light wavelength. Further, the lightdeflecting apparatus 10 f is operative with a relatively low drivingvoltage and has a stable mechanical strength for usage over an extendedperiod of time with lesser variations or degradation in the mechanism.

In addition, the method explained with reference to FIGS. 51–59 iscapable of achieving the micromachining and the integration machining ina relatively low cost, while requiring no specific use environment tothe resultant light deflecting apparatus 10 f.

Referring to FIGS. 62–71, another exemplary method of making a lightdeflecting apparatus is explained. In this discussion, a lightdeflecting apparatus to be made is referred to as a light deflectingapparatus 10 p. The light deflecting apparatus 10 p is similar to thelight deflecting apparatus 10 f of FIG. 23, except for the relativelysmall convex portion 2 a ₁ at substantially the central position of theplate 2 a in contact with the supporting member 4, which is the featureof the light deflecting apparatus 10 a of FIG. 6.

In this method, a first process provides a silicon oxide film on thesilicon substrate 3 with the plasma CVD (chemical-vapor deposition)method. Then, the photography using a photomask having a pattern with anarea coverage modulation or the photography which thermally deforms aresist pattern is used to form a resist pattern having an approximateshape and a thickness of the supporting member 4 c. After that, theformed resist pattern is deformed to an exact shape of the supportingmember 4 c with the dry etching method, as shown in FIG. 62.

In the above process, the silicon oxide film having a thickness ofapproximately 2 μm may be formed, and the works for forming thesupporting member 4 c may be performed in an upper layer ofapproximately 1 μm.

The height of the top of the supporting member 4 c is approximately 1μm.

A subsequent process provides the electrodes 6 (e.g., the electrodes 6 f₁–6 f ₄) made of a titanium nitride film. In this process, a titaniumnitride film is formed to have a thickness of 0.01 μm with the DCmagnetron sputtering process and is patterned into the electrodes 6 withthe photography and the dry etching method.

Then, a next process provides a protection layer 6 f ₅ made of a siliconnitride film having a thickness of 0.2 μm with the plasma CVD method.This protection layer 6 f ₅ is formed to protect the surfaces of theelectrodes 6 f ₁–6 f ₄ (see FIG. 64).

A next process forms a noncrystalline silicon film having a thickness of2 μm on the protection layer 6 f ₅ with the sputtering method, and thenoncrystalline silicon film is smoothed through a process time controlusing the CMP (chemical mechanical polishing). In this example, theprocess time control is conducted with reference to a time period inthat the thickness of the noncrystalline silicon film on the top of thesupporting member 4 c is completely removed and the supporting member 4c is exposed outside. In addition, the CMP is set to conditions in thatthe supporting member 4 c and the protection layer 6 f ₅ are morepolished so that, around the top portion of the supporting member 4 c, asupporting point of the supporting member 4 c remains and thenoncrystalline silicon film remains at a level lower than the supportingpoint of the supporting member 4 c. The supporting point of thesupporting member 4 c is projected by approximately 0.2 μm. Thenoncrystalline silicon film remaining on the protection layer 6 f ₅ isreferred to as a first sacrifice layer 7 (see FIG. 65).

As an alternative to the noncrystalline silicon film, the firstsacrifice layer 7 may be made of a polyimide film or a photosensitiveorganic film, or a resist film or a polycrystalline silicon film whichare generally used in a semiconductor process. The smoothing method maybe the etch back method with the dry etching.

In a next process, a noncrystalline silicon film of a 0.1-μm thick isformed on the first sacrifice layer 7 with the sputtering method (seeFIG. 66). This noncrystalline silicon film formed on the first sacrificelayer 7 is referred to as a third sacrifice layer 7 b.

Then, a next process forms a silicon nitride layer of a 0.2-μm thick onthe first sacrifice layer 7 with the plasma CVD method and subsequentlyforms an aluminum metal film of a 0.05-μm thick on the silicon nitridelayer with the sputtering method. After that, the aluminum metal film ispatterned into a conductive area of the plate 2 combining the reflectingsurface 1 a and the silicon nitride layer is then patterned into theplate 2 with the convex portion 2 a ₁, by the photography and the dryetching method (see FIG. 67).

A next process provides a noncrystalline silicon film of a 1-μm thick onthe conductive area of the plate 2 with the sputtering method. Thisnoncrystalline silicon film is referred to as a second sacrifice layer 7a (see FIG. 68). The second sacrifice layer 7 a may made of a polyimidefilm or a photosensitive organic film, or a resist film orpolycrystalline silicon film which are generally used in a semiconductorprocess.

A subsequent process divides each light deflecting apparatus withpatterns of the first, second, and third sacrifice layers 7, 7 a, and 7b together using the photography and the dry etching method. At thistime, the pattern areas of the first, second, and third sacrifice layers7, 7 a, and 7 b are slightly larger than the area of the plate 2including the conductive area combined with the reflecting surface 1 aof the reflecting member 1 (see FIG. 69). This process prepares for anext process for providing the angle brackets 5 around the plate 2.

FIG. 70 shows a process for forming the angle brackets 5 (i.e., theangel brackets 5 a ₁–5 a ₄). In this process, a silicon oxide film of a0.8-μm thick is formed with the plasma CVD method and is patterned tomake the angle brackets 5 with the photography and the dry etchingmethod.

Then, a final process removes the remaining first, second, and thirdsacrifice layers 7, 7 a, and 7 b through an opening with the wet etchingmethod so that the plate 2 is supported by the supporting member 4 c fora free movement within the free space G. Thus, the procedure for makingthe light deflecting apparatus 10 p is completed (see FIG. 71).

In this process, the angle brackets 5 are positioned at the four cornersof the first, second, and third sacrifice layers 7, 7 a, and 7 b in thesubstantially square shape with leaving the four sides open andtherefore the etching removal can be completed in a relatively shortperiod of time.

In the process for forming the angle brackets 5 shown in FIG. 70, theangel brackets 5 may have other shapes as shown in FIGS. 60 and 61, forexample.

In the thus-made light deflecting apparatus 10 p with the methodexplained with reference to FIGS. 62–71, the plate 2 a has therelatively small convex portion 2 a ₁, at substantially the centralposition thereof in contact with the supporting member 4 and istherefore capable of moving about the convex portion 2 a ₁, withoutdisengaging from the supporting member 4 c. Therefore, the lightdeflecting apparatus 10 p can stably perform a fast-responsive lightdeflection in directions with one deflection-axis or two deflection-axesby a simple control with a simple structure without restricting an inputlight wavelength. Further, the light deflecting apparatus 10 p isoperative with a relatively low driving voltage and has a stablemechanical strength for usage over an extended period of time withlesser variations or degradation in the mechanism.

In addition, the method explained with reference to FIGS. 62–71 iscapable of achieving the micromachining and the integration machining ina relatively low cost, while requiring no specific use environment tothe resultant light deflecting apparatus 10 p.

Referring to FIGS. 72–80, another exemplary method of making a lightdeflecting apparatus is explained. In this discussion, a lightdeflecting apparatus to be made is an apparatus similar to the lightdeflecting apparatus 10 j of FIG. 41, as an example. A first processprovides a resist pattern on the silicon substrate 3 j with thephotography using a photomask having a pattern with an area coveragemodulation or a density modulation. This resist pattern has anapproximate shape and a thickness of the hollows 3 j, or the roof-likeslopes 3 j ₂ serving as the supporting member. After that, the formedresist pattern is deformed to the roof-like slopes 3 j ₂ serving as thesupporting member with the dry etching method, as shown in FIG. 72.Then, in order to have an insulation to the substrate 3 j, a siliconoxide film is formed to a thickness of approximately 1 μm on theroof-like slopes 3 j ₂ by the plasma CVD. Thereby, the hollows 3 j ₁ areformed, and the roof-like slopes 3 j ₂ covered with the silicon oxidefilm of a 1-μm thick, serving as the supporting member, are provided onthe substrate 3 j.

In the above process, the silicon oxide film having a thickness ofapproximately 2 μm may be formed, and the works for forming thesupporting member may be performed in an upper layer of approximately 1μm.

The height of the top of the supporting member is approximately 0.3 μm.

A subsequent process provides the electrodes 6 (i.e., the electrodes 6 f₁–6 f ₄) made of a titanium nitride film (see FIG. 73). In this process,a titanium nitride film is formed to have a thickness of 0.01 μm withthe DC magnetron sputtering process and is patterned into the electrodes6 f ₁–6 f ₄ with the photography and the dry etching method.

Then, a next process provides a protection layer 6 f ₅ made of a siliconnitride film having a thickness of 0.2 μm with the plasma CVD method.This protection layer 6 f ₅ is formed to protect the surfaces of theelectrodes 6 f ₁–6 f ₄ (see FIG. 74).

A next process forms a noncrystalline silicon film having a thickness of2 μm on the protection layer 6 f ₅ with the plasma CVD. Then, thenoncrystalline silicon film is polished to be smoothed, with the CMP. Inthis polishing, the substrate 3 j and the protection layer 6 f ₅ areused as etching stop layers.

In this process, the noncrystalline silicon film in the hollows 3 _(j) 1is not over-polished due to the effect of the etching stop layers, sothat the smoothing of the noncrystalline silicon film is achieved undera high precision control.

In this example, the thickness of the noncrystalline silicon filmremaining on the top of the supporting member is reduced to 0.2 μm. Thenoncrystalline silicon film remaining on the protection layer 6 f ₅ isreferred to as a first sacrifice layer 7 (see FIG. 75).

As an alternative to the noncrystalline silicon film, the firstsacrifice layer 7 may be made of a polyimide film or a photosensitiveorganic film, or a resist film or a polycrystalline silicon film whichare generally used in a semiconductor process. The smoothing method maybe a reflow method with a thermal processing or an etch back method withthe dry etching.

Then, a next process forms a silicon nitride layer of a 0.2-μm thick onthe first sacrifice layer 7 with the plasma CVD method and subsequentlyforms an aluminum metal film of a 0.05-μm thick on the silicon nitridelayer with the sputtering method. After that, the aluminum metal film ispatterned into a conductive area of the plate 2 combining the reflectingsurface 1 a and the silicon nitride layer is patterned into the plate 2,with the photography and the dry etching method (see FIG. 76).

A next process provides a noncrystalline silicon film of a 1-μm thick onthe conductive area of the plate 2 with the sputtering method. Thisnoncrystalline silicon film is referred to as a second sacrifice layer 7a (see FIG. 77). The second sacrifice layer 7 a may made of a polyimidefilm or a photosensitive organic film, or a resist film orpolycrystalline silicon film which are generally used in a semiconductorprocess.

A subsequent process divides each light deflecting apparatus withpatterns of the first and second sacrifice layers 7 and 7 a togetherusing the photography and the dry etching method. At this time, thepattern areas of the first and second sacrifice layers 7 and 7 a areslightly larger than the area of the plate 2 including the conductivearea combined with the reflecting surface 1 a of the reflecting member 1(see FIG. 78). This process prepares for a next process for providingthe angle brackets 5 around the plate 2.

FIG. 79 shows a process for forming the angle brackets 5 (i.e., theangel brackets 5 a ₁–5 a ₄). In this process, a silicon oxide film of a0.8-μm thick is formed with the plasma CVD method and is patterned tomake the angle brackets 5 with the photography and the dry etchingmethod.

Then, a final process removes the remaining first and second sacrificelayers 7 and 7 a through an opening with a wet etching method so thatthe plate 2 is supported by the supporting member for a free movementwithin the free space G. Thus, the procedure for making the lightdeflecting apparatus 10 j shown in FIG. 41 is completed (see FIG. 80).

In this process, the angle brackets 5 are positioned at the four cornersof the first and second sacrifice layers 7 and 7 a in the substantiallysquare shape with leaving the four sides open and therefore the etchingremoval can be completed in a relatively short period of time.

In the process for forming the angle brackets 5 shown in FIG. 79, theangel brackets 5 may have other shapes as shown in FIGS. 60 and 61, forexample.

The thus-made light deflecting apparatus 10 j with the method explainedwith reference to FIGS. 72–80 is capable of stably performing afast-responsive light deflection in directions with one deflection-axisor two deflection-axes by a simple control with a simple structurewithout restricting an input light wavelength. Further, the lightdeflecting apparatus 10 j is operative with a relatively low drivingvoltage and has a stable mechanical strength for usage over an extendedperiod of time with lesser variations or degradation in the mechanism.

In addition, the method explained with reference to FIGS. 72–80 iscapable of achieving the micromachining and the integration machining ina relatively low cost, while requiring no specific use environment tothe resultant light deflecting apparatus 10 j.

Next, the image forming apparatus 200 is explained with reference toFIG. 81. FIG. 81 shows the image forming apparatus 200 which forms animage by optically writing image data with an electrophotographicmethod. The image forming apparatus 200 includes an image carryingmechanism 201, a latent image forming mechanism 202, a developmentmechanism 203, a transfer mechanism 204, a charging mechanism 205, afixing mechanism 206, a sheet ejecting tray 207, and a cleaningmechanism 208.

The image carrying mechanism 201 includes a drum-shaped photosensitivesurface and is rotated in a direction C8. The image carrying mechanism201 is evenly charged by the charging mechanism 205. The latent imageforming mechanism 202 forms a latent image on the photosensitive surfaceof the image carrying mechanism 201. The development mechanism 203develops with toner the latent image formed on the photosensitivesurface of the image carrying mechanism 201. The transfer mechanism 204transfers the toner image onto a recording sheet V. The fixing mechanism206 fixes the toner image to the recording sheet V with heat andpressure. The recording sheet V is ejected to the sheet ejecting tray207. The cleaning mechanism 208 cleans off the photosensitive surface ofthe image carrying mechanism 201.

As shown in FIG. 81, the latent image forming mechanism 202 includes anoptical information processing apparatus 100 which includes the lightdeflecting apparatus 20 of FIG. 49, i.e., a one-dimension lightdeflection array, including a plurality of the above-described lightdeflecting apparatuses 10, for example, arranged in a one-dimensionformation. The optical information processing apparatus 100 furtherincludes a driving mechanism 101, a light source 102, a first lenssystem 103, and a second lens system 104.

In the optical information processing apparatus 100, the light source102 emits light W1 which travels through the first lens system 103 toeach of the light deflecting apparatuses 10 of the light deflectingapparatus 20. The driving mechanism 101 independently drives each of thelight deflecting apparatuses 10 of the light deflecting apparatus 20 inaccordance with input image data. That is, the driving mechanism 101independently changes the reflection angle relative to the input lightW1 by changing the position of the plate 2 in each light deflectingapparatus 10 according to the input image data. Therefore, thereflection of the light W1 towards the photosensitive surface of theimage carrying member 201 is controlled according to the input imagedata by the light deflecting apparatus 20. The light W1 reflected by thelight deflecting apparatus 20 travels through the second lens system 104to the photosensitive surface to form a latent image. Thus, the imageforming apparatus 200 including the light deflecting apparatus 20effectively forms an image according to the input image data.

Next, the image projection display apparatus 300 is explained withreference to FIG. 82. FIG. 82 shows the image projection displayapparatus 300 which projects an image by deflecting light of an image.The image projection display apparatus 300 includes a light switchingmechanism 301 and a projection screen 302. The light switching mechanism301 includes an optical information processing apparatus 100 a whichincludes the light deflecting apparatus 30 of FIG. 50, i.e., atwo-dimension light deflection array, including a plurality of theabove-described light deflecting apparatuses 10, for example, arrangedin a two-dimension formation. The optical information processingapparatus 100 a further includes the driving mechanism 101, the lightsource 102, a projection lens 105, an aperture 106, a rotary color hole107, and a micro-lens array 108.

In the optical information processing apparatus 100 a, the light source102 emits light W2 which travels, through the rotary color hole 107 fora color display and the micro-lens array 108 for a high precision, toeach of the light deflecting apparatuses 10 of the light deflectingapparatus 30. The driving mechanism 101 independently drives each of thelight deflecting apparatuses 10 of the light deflecting apparatus 30 inaccordance with input image data. That is, the driving mechanism 101independently changes the reflection angle relative to the input lightW2 by changing the position of the plate 2 in each light deflectingapparatus 10 according to the input image data. Therefore, thereflection of the light W2 towards the screen 302 is controlledaccording to the input image data by the light deflecting apparatus 30.The light W2 reflected by the light deflecting apparatus 30 travelsthrough the projection lens 105 and the aperture 106 to the screen 302to form an image. Thus, the image projection display apparatus 300including the light deflecting apparatus 30 effectively projects adesired image on the screen.

Next, the optical data transmission apparatus 400 is explained withreference to FIG. 83. FIG. 83 shows the optical data transmissionapparatus 400 for transmitting an optical data signal. The optical datatransmission apparatus 400 includes an optical data input mechanism 401,an optical data switching mechanism 402, and an optical data outputmechanism 403.

The optical data input mechanism 401 includes a plurality oftransmission ports, including transmission ports 401 a ₁, 401 a ₂, and401 a ₃, for example, for inputting optical data signals to the opticaldata switching mechanism 402. The optical data switching mechanism 402includes light deflection controllers 402 a ₁ and 402 a ₂ andcorresponding two stages of the light deflecting apparatuses 30 of FIG.50, i.e., a two-dimension light deflection array, each including aplurality of the above-described light deflecting apparatuses 10, forexample, arranged in a two-dimension formation. Each of light deflectioncontrollers 402 a ₁ and 402 a ₂ independently and simultaneously drivesthe plurality of light deflecting apparatuses 10 included in each of thetwo light deflecting apparatuses 30. The optical data switchingmechanism 402 determines light reflection directions with respect to theinput optical data signals by switching the light reflection angles inthe one-dimension direction or in the two-dimension direction of theplate 2 in each of the light deflecting apparatus 10 of the lightdeflecting apparatus 30. The optical data output mechanism 403 includesa plurality of transmission ports, including transmission ports 401 b ₁,401 b ₂, and 401 b ₃, for example, for outputting the optical datasignals emitted from the optical switching mechanism 402.

Thus, the optical data transmission apparatus 400 including the lightdeflecting apparatus 30 effectively transmits the optical data.

In the above-described optical data switching mechanism 402, the lightdeflection angle is made relatively large by having the two stages ofthe light deflecting apparatus 30. However, a single stage of the lightdeflecting apparatus 30 may be used when the number of the selectabletransmission ports is relatively small.

Referring to FIGS. 84 and 85, a light deflecting apparatus 10 qaccording to another preferred embodiment of the present invention isexplained. FIG. 84 is a plane view of the light deflecting apparatus 10q, and FIG. 85 is a cross-section view of the light deflecting apparatus10 q taken on line AA—AA of FIG. 84. The light deflecting apparatus 10 qof FIG. 84 is an apparatus modified on the basis of the light deflectingapparatus 10 c of FIG. 12, that is, the supporting member 4 c ismodified to a supporting member 4 q having a pyramid shape. The top ofthe supporting member 4 q is preferably rounded to disperse the stress,but it may also be pointed. The supporting member 4 q is made of asilicon oxide film or a silicon nitride film, for example, and thereforeit may have a relatively high mechanical strength.

Referring to FIGS. 86 and 87, a light deflecting apparatus 10 raccording to another preferred embodiment of the present invention isexplained. FIG. 86 is a plane view of the light deflecting apparatus 10r, and FIG. 87 is a cross-section view of the light deflecting apparatus10 r taken on line AA—AA of FIG. 86. The light deflecting apparatus 10 rof FIG. 86 is an apparatus modified on the basis of the light deflectingapparatus 10 c of FIG. 12, that is, the supporting member 4 c ismodified to a supporting member 4 r having a pyramid shape which basehas an area substantially equal to that of the plate 2. With thisstructure, the plate 2 can stably maintain its position when tilted dueto the electrostatic attraction force since the supporting surface ofthe supporting member 4 r is wide.

Referring to FIG. 88, a light deflecting apparatus 10 s according toanother preferred embodiment of the present invention is explained. FIG.88 is a plane view of the light deflecting apparatus 10 s. The lightdeflecting apparatus 10 s of FIG. 88 is an apparatus modified on thebasis of the light deflecting apparatus 10 k of FIG. 42, that is, thesupporting member 4 is modified to an octagonal pyramid supportingmember 4 s and the four-piece electrodes 6 k ₁–6 k ₄ are modified toeight pieces of corresponding triangular electrodes 6 s ₁–6 s ₈. Inaddition, the single circumferential angle bracket 5 k is modified tofour piece angle brackets 5 _(s) ₁–5 s ₄.

For example, when the electrodes 6 s ₁–6 s ₈ are applied with thefollowing voltages:

6 s ₁–6 s ₅; Y/2 volts,

6 s ₆; Y volts,

6 s ₇; Y/2 volt, and

6 s ₈; 0 volts,

the plate 2 k is attracted by the electrostatic attraction forces actingbetween the plate 2 k and the electrode 6 s ₆ and between the plate 2 kand the electrode 6 s ₈ and is eventually tilted to sit on the portionof the supporting member 4 ka corresponding to the electrode 6 s ₇existing between the electrodes 6 s ₆ and 6 s ₈.

The base area of the octagonal pyramid supporting member 4 s ispreferably close to the area of the plate 2 k so that the plate 2 kstably sits on the corresponding portion of the supporting member 4 s.

In this example, the four angle brackets 5 s ₁–5 s ₄ are discretelydisposed on the circular edge of the substrate 3. Whether such discretearrangement or the single circumferential arrangement as shown in FIG.42 may be determined when an entire array structure is designed.

The shape of the supporting member 4 s is not limited to the octagonalpyramid and may be any polygonal pyramid such as a hexagonal pyramid, aheptagonal pyramid, a decagonal pyramid, and so forth. For example, whenthe supporting member 4 s is a hexagonal pyramid, the light deflectionis made with three axes. Likewise, an octagonal pyramid member makes thelight deflection with four axes and a decagonal pyramid member makes thelight deflection with five axes.

Furthermore, even if the supporting member has a conical shape, theplate 2 k may effectively tilt with the electrode divided into anarbitrary plural electrically-isolated pieces such as the electrodes 6ka ₁–6 ka ₈, although the plate 2 k may not stably sit on such conicalshape supporting member.

Referring to FIGS. 89 and 90, a light deflecting apparatus 10 taccording to another preferred embodiment of the present invention isexplained. FIG. 89 is a plane view of the light deflecting apparatus 10t, and FIG. 90 is a cross-section view of the light deflecting apparatus10 t taken on line CC—CC of FIG. 89. The light deflecting apparatus 10 tof FIG. 89 is an apparatus modified on the basis of the light deflectingapparatus 10 of FIG. 1, that is, the plate 2 is modified to asingle-layered plate 2 t made of a material such as aluminum having arelatively high reflectance. With the aluminum single-layered plate 2 t,the plate is not needed to have an extra reflecting member (e.g., thereflecting member 1).

Next, a light deflecting apparatus 2100 according to another preferredembodiment of the present invention with reference to FIGS. 91A and 91B.FIG. 91A is a plane view of the light deflecting apparatus 2100, andFIG. 91B is a cross-section view taken on line DD—DD of FIG. 91A. Thelight deflecting apparatus 2100 deflects input light into a signal axialreflective direction or two axial reflective directions. As shown inFIGS. 91A and 91B, the light deflecting apparatus 2100 includes asubstrate 2101, an angle bracket 2102, a supporting member 2103, and aplate 2104.

The substrate 2101 may be made of any material but is preferably, inconsideration of miniaturization, a material generally used in asemiconductor process or a liquid crystal process, such as silicon,glass, or the like. The substrate 2101 may be combined with a drivingcircuit substrate (not shown) having a plane direction (100) to make thelight deflecting apparatus 2100 in a simple and lower cost structure.

The angle brackets 2102 have a stopper 2102 a at one end thereof forstopping the plate 2104. The angle brackets 2102 are preferably made ofa material capable of being miniaturized and having a high mechanicalstrength in order to maximize an area ratio of the reflection region,particularly, when a plurality of the light reflecting apparatuses areminiaturized into an array form. In addition, since the angle brackets2102 are likely to be obstacles to the mirroring operation, the anglebrackets 2102 are preferably made of a translucent material such as asilicon oxide film so as to minimize a loss of the mirroring capability.However, when a scattering is being concerned, the angle brackets 2102may be subjected to a treatment of providing a nature of an opticalabsorption to the surface thereof.

The supporting member 2103 preferably has a conical shape and its topportion 2103 a serves as a fulcrum for the movement of the plate 2104.However, the shape of the supporting member 2103 is not limited to thecone but any shape capable of being a fulcrum for the movement of theplate 2104. At least the top portion 2103 a of the supporting member2103 contacting the plate 2104 is conductive. The supporting member 2103needs to have a good conductivity and a high mechanical strength, and ispreferably made of a crystal silicon film or a polycrystalline siliconfilm, having a low resistivity, a metal film, a metal silicide film suchas a tungsten silicide film and a titan silicide film, or amulti-layered film including a metal film and an insulation film such asa silicon oxide film and a silicon nitride film. In the case of themulti-layered film including a metal film and an insulation film, apotential applying line for applying a potential to the plate 2104 and aconnection hole for connecting the metal film.

The plate 2104 has no edge portion fixed, and is movably held on the topportion 2103 a of the supporting member 2103. The plate 2104 moveswithin a predetermined space determined by the substrate 2101, thesupporting member 2103, the angle brackets 2102, and the stoppers 2102a. The plate 2104 is entirely made of a conductive layer. However, theplate 2104 partly including a conductive layer on the upper or bottomsurface thereof may be used due to a reason of an action by anelectrostatic attraction force, later explained.

The plate 2104 includes a contact portion 2104 a in a bottom sidethereof contacting the supporting member 2103 and, in the plate 2104, atleast the contact portion 2104 a is conductive. The contact portion 2104a may be the above-mentioned conductive layer or a separate portion.When the contact portion 2104 a is separate from the conductive portion,they are needed to be electrically connected. The plate 2104 needs tohave a good conductivity and a high mechanical strength and ispreferably made of a metal film including an aluminum, a chromium, atitanium, a gold, or a silver. When a light reflecting region 2104 b ofthe plate 2104 is an entire upper surface of the plate 2104, the plate2104 is preferably made of an aluminum metal having a superiorreflection capability. As described above, the plate 2104 is restrictedin moving within the predetermined space and, for this purpose, theangel brackets 2102 are arranged to allow the plate 2104 to tilt aboutthe contacting portion 2104 a supported by the top portion 2103 a of thesupporting member 2103. Furthermore, the plate 2104 is preferably planeand at least the light reflecting region 2104 b is preferably flat. Theflatness of the plate 2104 allows the light lays entering the lightreflecting region 2104 b to be reflected in an aligned direction. Theplate 2104 preferably has a radius of curvature of a few meters orgreater. The light reflecting region 2104 b may be referred simply to asa light reflecting surface when discussing merely on the lightreflecting function of the light reflecting region 2104 b.

The above-described feature by the flatness of the light reflectingregion 2104 b avoids an adverse effect to between adjacent opticaldevices and is therefore important in particular when the lightdeflecting apparatus 2100 is employed in optical equipment such as anoptical information processing apparatus, an image forming apparatus(e.g., an image forming apparatus 1300 explained later with reference toFIG. 103), an image projection display apparatus (e.g., an imageprojection display apparatus 1400 explained later with reference to FIG.104), an optical transmission apparatus (e.g., an optical datatransmission apparatus 1500 explained later with reference to FIG. 105),and so forth.

Referring to FIGS. 92A and 92B, a light deflecting apparatus 2100 aaccording to another preferred embodiment of the present invention isexplained. FIG. 92A is a plane view of the light deflecting apparatus2100 a, and FIG. 92B is a cross-section view of the light deflectingapparatus 2100 a taken on line EE—EE of FIG. 92A. The light deflectingapparatus 2100 a of FIG. 92A is an apparatus modified on the basis ofthe light deflecting apparatus 2100 of FIG. 91A, that is, the plate 2104is modified to a plate 2204 including a dielectric layer 2201 and aconductive layer 2202. In addition, the plate 2204 includes a contactingportion 2204 a which includes the conductive layer 2202 to contact thetop portion 2103 a of the supporting member 2103. The conductive layer2202 may be structured in a manner similar to the plate 2104 of FIG.91B. The dielectric layer 2201 preferably has a high dielectric strengthof three or greater. More preferably, the dielectric layer 2201 is madeof a silicon nitride film, having a dielectric strength of from 6 to 8and a high mechanical strength. Reference numeral 2204 b denotes anopening formed in the dielectric layer 2201 so that the contactingportion 2204 a contacts the top portion 2103 a. The opening 2204 b isformed with a patterning process by the photography.

Referring to FIGS. 93A and 93B, a light deflecting apparatus 2100 baccording to another preferred embodiment of the present invention isexplained. FIG. 93A is a plane view of the light deflecting apparatus2100 b, and FIG. 93B is a cross-section view of the light deflectingapparatus 2100 b taken on line FF—FF of FIG. 93A. The light deflectingapparatus 2100 b of FIG. 93A is an apparatus modified on the basis ofthe light deflecting apparatus 2100 of FIG. 91A, that is, fourelectrodes 2301 are provided to the upper surface of the substrate 2101.The electrodes 2301 are electrically separated from the conductive topportion 2103 a of the supporting member 2103. The electrodes 2301 needto be conductive and are made of metal such as an aluminum metal,titanium nitride, or a titanium. The electrodes 2301 are arranged suchthat at least a portion of the conductive layer included in the plate2104 faces the electrodes 2301. A space between the portions thus facingeach other is acted with an electrostatic attraction force generated dueto a difference between voltages applied to one of the electrodes 2301and to the plate 2104 via the supporting member 2103 so that the plate2104 is tilted in a desired direction. When the application of voltageto the electrode 2301 is changed to another electrode 2301, the plate2104 can quickly move in another direction. Thus, by arbitrarilychanging the application of the voltage to the four electrodes 2301, thetilt movement of the plate 2104 can be controlled with tow-axisdirections in a high precision manner.

Referring to FIGS. 94A and 94B, a light deflecting apparatus 2100 caccording to another preferred embodiment of the present invention isexplained. FIG. 94A is a plane view of the light deflecting apparatus2100 c, and FIG. 94B is a cross-section view of the light deflectingapparatus 2100 c taken on line GG—GG of FIG. 94A. The light deflectingapparatus 2100 c of FIG. 94A is an apparatus modified on the basis ofthe light deflecting apparatus 2100 of FIG. 91A, that is, the supportingmember 2103 is modified to a supporting member 2401 having a rectangularsolid shape. In addition, the angle brackets 2102 are modified to anglebrackets 2102 c differently shaped and arranged from those of the lightdeflecting apparatus 2100 of FIG. 91A. As shown in FIG. 95A, thesupporting member 2401 has a ridgeline supporting the plate 2104 and twowide area slopes for contacting the plate 2104 when the plate 2104 istilted. With this ridgeline of the supporting member 2401, the plate2104 can arbitrarily be tilted in directions with one deflection-axis.The shape of the supporting member 2401 is not limited to that shown inFIG. 95A. For example, a supporting member 2401 a having a rounded top,as shown in FIG. 95B, may be used as an alternative to the supportingmember 2401. For another example, a supporting member 2401 b havingpentagonal rectangular solid shape, as shown in FIG. 95C, may also beused as an alternative to the supporting member 2401.

Referring to FIGS. 96A and 96B, a light deflecting apparatus 2100 daccording to another preferred embodiment of the present invention isexplained. FIG. 96A is a plane view of the light deflecting apparatus2100 d, and FIG. 96B is a cross-section view of the light deflectingapparatus 2100 d taken on line HH—HH of FIG. 96A. The light deflectingapparatus 2100 d of FIG. 96A is an apparatus modified on the basis ofthe light deflecting apparatus 2100 c of FIG. 94A, that is, thesupporting member 2401 is modified to a supporting member 601 having atriangular solid shape. As shown in FIG. 96A, the supporting member 601has wide two roof-like-shaped slopes corresponding to nearly an entirearea of the plate 2104 and is attached with the four electrodes 2301thereon. The supporting member 601 are preferably made of an insulatingmaterial to electrically separate the electrodes 2301 from each otherbut includes a top portion 602 made of a conductive material to apply avoltage to the plate 2104. The top portion 602 is preferably formedtogether with the supporting member 601 at the same time into the samefilm.

In addition, to prevent an occurrence of a short circuit between theplate 2104 and the electrodes 2301 when the plate 2104 is tilted andcontacts the electrodes 2301, the electrodes 2301 are covered with aninsulating film 603 which is preferably made of an insulating materialsuch as a silicon oxide film or a silicon nitride film. As analternative to the insulating film 603, the plate 2104 may include thedielectric layer 2201, as explained with reference to FIG. 92B. Theinsulating film 603 is needed to have an opening for allowing anconnection to the top portion 602 of the supporting member 601.

With this structure, a portion of the electrodes 2301 comes closer tothe plate 2104 as it is closer to the ridgeline thereof and accordinglya greater electrostatic attraction force is generated. In other words,the plate 2104 can be driven with a smaller voltage. Also, the contactof the plate 2104 with the slopes of the supporting member 601 is madewith their surfaces and accordingly the impact of the contact can bedispersed. Therefore, the movement of the plate 2104 can stably becontrolled.

Referring to FIGS. 97A and 97B, a light deflecting apparatus 2100 eaccording to another preferred embodiment of the present invention isexplained. FIG. 97A is a plane view of the light deflecting apparatus2100 e, and FIG. 97B is a cross-section view of the light deflectingapparatus 2100 e taken on line II—II of FIG. 97A. The light deflectingapparatus 2100 e of FIG. 97A is an apparatus modified on the basis ofthe light deflecting apparatus 2100 d of FIG. 96A, that is, theinsulating film 603 is modified to an insulating film 604 having aplurality of small circular projections 701 arbitrarily arrangedrelative to the slope surfaces of the supporting member 601. Thedirection of the light reflection is determined by the contact of theplate 2104 with these small circular projections 701 of the insulatingfilm 604. The plurality of small circular projections 701 are preferablymade by a process of patterning an insulating film (e.g., the insulatingfilm 604), which is later explained.

The size, height, and pitch of the projections 701 can be determined ona basis of a relationship between the electrostatic attraction force anda stiffness of the plate 2104. The shape of the projections 701 mayfreely be determined within a limit that the plate 2104 does not contactthe electrodes 2301 due to its deformation. When the plate 2104 is athin film having a high stiffness, it resists being deformed. Therefore,in this case, the projections 701 can be formed with a small size, a lowheight, and small pitch. With such structure, the contact area betweenthe projections 701 and the plate 2104 can be made small and, as aresult, an adhesion of the projections 701 and the plate 2104 can beavoided in a usage for an extended period of time.

Referring to FIGS. 98A–98K, a light deflecting apparatus 2100 faccording to another preferred embodiment of the present invention isexplained. FIG. 98A is a plane view of the light deflecting apparatus2100 f. FIGS. 98B and 98C are cross-section views of the lightdeflecting apparatus 2100 f taken on line JJ—JJ and line KK—KK,respectively, of FIG. 98A. FIGS. 98D–98K explain operations of the lightdeflecting apparatus 2100 f.

In the light deflecting apparatus 2100 f of FIG. 98A, the substrate2101, the supporting member 2103, the plate 2204 including thedielectric layer 2201, the conductive layer 2202, the contacting portion2204 a, and the opening 2204 b are equivalent to those of the lightdeflecting apparatus 2100 a of FIG. 92B. The angle brackets 2101 c areequivalent to those of the light deflecting apparatus 2100 c of FIG.94B. Further, reference numerals 800, 800 b, 800 c, and 800 d denoteelectrodes which are equivalent to the electrodes 2301 of the lightdeflecting apparatus 2100 b of FIG. 93B. Further, reference numerals 801and 802 denote a dielectric layer and a conductive layer, respectively,of the supporting member 2103. The electrodes 800 a–800 d are arrangedto face the plate 2204 having the dielectric layer 2201 and theconductive layer 2202, and are made of the same material as theelectrodes 2301. The top portion 2103 a of the supporting member 2103 isformed in a multi-layered form including the dielectric layer 801 madeof an insulating silicon film and the conductive layer 802. Theconductive layer 802 is made of the same material as the electrodes 800a–800 d and is patterned together with the electrodes 800 a–800 d.

In the following discussion, the views of FIGS. 98D, 98F, 98H, and 98Jshow the movements of the plate 2204 with a first axis taken on lineLL—LL, and the views of FIGS. 98E, 98G, 98I, and 98K show the movementsof the plate 2204 with a second axis taken on line JJ—JJ.

FIG. 98D and 98E are cross section views of the light deflectingapparatus 2100 f taken on line JJ—JJ and line LL—LL, respectively, ofFIG. 98A, and are virtually made, for the sake of clarity, todemonstrate a condition when the light deflecting apparatus 2100 f is inan initial status, in consideration of the nature that the plate 2204 isfreely movable with being held by the supporting member 2103.

FIGS. 98F and 98G are cross section views of the light deflectingapparatus 2100 f taken on line JJ—JJ and line LL—LL, respectively, ofFIG. 98A, demonstrating a reset operation of the light deflectingapparatus 2100 f. When the light deflecting apparatus 2100 f settled inthe initial status performs the reset operation, the plate 2204 is movedfrom the position in the initial status of FIGS. 98D and 98E to a resetposition, as shown in FIGS. 98F and 98G, respectively. In the resetposition, the plate 2204 has one edge portion (e.g., a portion 2204 c)contacting the substrate 2101 with the central portion being supportedby the supporting member 2103.

In the reset operation, the electrodes 800 a and 800 d are applied witha voltage of X volts, for example, and the electrodes 800 c and 800 dand the conductive layer 802 are applied with a voltage of 0 volts, forexample. With the application of these voltages, an electrostaticattraction force is generated between the plate 2204 and the electrodes800 a–800 d and the conductive layer 802 in a direction indicated bywhite arrows indicated underneath the plate 2204, as shown in FIG. 98Dand 98E. The white arrows of FIGS. 98D and 98E and those of FIGS.98F–98K and FIG. 99 schematically indicate, by size, directions andmagnitudes of the electrostatic attraction force acting between theplate 2204 and the electrodes 800 a–800 d, as the electrostaticattraction force varies depending upon a portion of the plate 2204.

Accordingly, the white arrows in FIG. 98F schematically indicate thatmagnitudes of the electrostatic attraction force acting between theplate 2204 and the electrodes 800 a–800 d are uneven, and therefore theplate 2204 is tilted to the reset position by the electrostaticattraction force. FIG. 98G shows this tilting movement from a 90-degreedifferent angle which is the view taken on line LL—LL. In FIG. 98G, asthe white arrows indicate, the electrostatic attraction force evenlyacts between the plate 2204 and the electrodes 800 a–800 d, andtherefore the movement of the plate 2204 is not seen in the view of FIG.98G. That is, the view of FIG. 98F shows the tilt movement of the plate2204 in the first axis direction and the view of FIG. 98G shows the tiltmovement of the plate 2204 in the second axis direction. Thus, the angleof the plate 2204 is changed and the light reflecting angle is directedin a desired direction which is referred to as a reset direction. As theplate 2204 is moved in the reset direction, its edge portion (e.g., aportion 2204 d) contacts the substrate 2101. In this situation, thelight deflecting apparatus 2100 f is said to be in a reset status.

The above-mentioned voltage of X volts is determined according tovarious factors including distances between the plate 2204 and each ofthe electrodes 800 a–800 d and capacitances of the plate 2204 and theelectrodes 800 a–800 d, for example. This voltage of X volts required inthe reset operation is slightly greater than a voltage Z required in aregular tilting operation for moving the plate 2204 held on thesupporting member 2103.

FIGS. 98H and 98I are cross section views of the light deflectingapparatus 2100 f taken on line JJ—JJ and LL—LL, respectively, of FIG.98A, demonstrating a first operation of the light deflecting apparatus2100 f. When the light deflecting apparatus 2100 f staying in the resetposition, as shown in FIGS. 98F and 98G, performs the first operation,the plate 2204 is tilted in an opposite direction and changes itsposition from the reset position of FIGS. 98F and 98G to a firstposition shown in FIGS. 98H and 98I. In the first position, the plate2204 has an edge portion (e.g., a portion 2204 d) contacts the substrate2101 with being held by the supporting member 2204. Thus, the lightdeflecting apparatus 2100 f can quickly change the direction of thelight deflection with the first axis. In the first operation, theelectrodes 800 a and 800 b are applied with a voltage of 0 volts, forexample, and the electrodes 800 c and 800 d are applied with a voltageof X volts.

When the same bias voltages of either positive or negative are added tothe voltages of the electrodes and the conductive layer (i.e., the plate2204), it causes no voltage difference at any portion between theelectrodes and the conductive layer. In this case, the plate 2204 doesnot change its position. That is, the electrostatic attraction force isgenerated not by the voltage itself but by the voltage differenceexisting between the electrodes and the conductive layer.

In this example, the voltages applied to the electrodes 800 a–800 d arechanged, while maintaining the application of the voltage of 0 volts tothe conductive layer 802. However, to merely switch the position of theplate 2204 from the reset position to the first position, it can simplybe achieved by changing the application of the voltage to the conductivelayer 802. That is, the application of the voltage to the conductivelayer 802 is changed from 0 volts to X volts while maintaining theapplications of the voltage of X volts to the electrodes 800 a and 800 band of 0 volts to the electrodes 800 c and 800 d. In this way, the plate2204 can be settled in the reset position by the application of avoltage of 0 volts and in the first position by the application of avoltage of X volts.

Thus, the plate 2204 receives a greater electrostatic attraction forcein its one-half side when there is a voltage difference between theone-half side of the plate 2204 and the electrode or when a voltagedifference between the one-half side of the plate 2204 and the electrodeis greater than that between the other one-half of the plate 2204 andthe electrode. As a consequence, the plate is moved in the directionattracted. That is, the tilt directions of the plate 2204 can beswitched at a high speed by applying arbitrary voltages to theelectrodes 800 a–800 d opposing to each other relative to the supportingmember 2103 to equalize the voltage of the conductive layer 802 to thevoltage of one of the electrodes 800 a–800 d.

FIGS. 98J and 98K are cross section views of the light deflectingapparatus 2100 f taken on line JJ—JJ and LL—LL, respectively, of FIG.98A, demonstrating a second operation of the light deflecting apparatus2100 f. When the light deflecting apparatus 2100 f settled in the resetstatus shown in FIGS. 98F and 98G performs the second operation, theplate 2204 is tilted, as shown in FIG. 98K, and changes its positionfrom the reset position of FIGS. 98F and 98G to a second position shownin FIGS. 98J and 98K. In this case, the tilting movement of the plate2204 shown in FIGS. 98J and 98K is made about the second axis taken online JJ—JJ. In the second position, the plate 2204 has an edge portion(e.g., a portion 2204 e) contacts the substrate 2101. Thus, the lightdeflecting apparatus 2100 f changes the direction of the lightdeflection with the second axis. In the second operation, the electrodes800 a, 800 c, and the conductive layer 802 are applied with a voltagesof 0 volts, and the electrodes 800 b and 800 d are applied with avoltage of X-volts.

In this way, the light deflecting apparatus 2100 f changes the directionof the light deflection with the first and second axes by the first andsecond operations applying the above-described voltages to theelectrodes 800 a–800 d and the conductive layer 802. Therefore, thelight deflecting apparatus 2100 f has four different light reflectiondirections.

With reference to FIG. 99, the principle of the electrostatic attractionis explained. FIG. 99 is a cross section view of the light deflectingapparatus 2100 f, for example, taken on line MM—MM of FIG. 98A. In FIG.99, the light deflecting apparatus 2100 f is in the reset operation,with the applications of a positive voltage of X volts to the electrode800 b and a voltage of 0 volts to 800 d. Initially, the plate 2204 is inan electrically floating status. When the electrode 800 b is appliedwith the positive voltage of X volts, it will have positive charges.Subsequently, negative charges appear in the dielectric layer 2201 ofthe plate 2204 facing the electrode 800 b in a dielectric manner via aspace 901. At the same time, the negative charges in the dielectriclayer 2201 are quickly dispersed in a conductive manner in theconductive layer 2202 of the plate 2. This can be expressed in such away that the negative charges are efficiently generated in thedielectric layer 2201 by the conductive layer 2202. Thereby, anelectrostatic attraction force is generated between the electrode 800 band the corresponding portion of the plate 2204 and the plate 2204 isattracted to the electrode 800 b.

On the other hand, the generation of the negative charges in the plate2204 subsequently cause a generation of positive charges in a dielectricmanner in the dielectric layer 2201 of the plate 2204 facing theelectrode 800 d via the space 901. The positive charges generated willschematically spread in the conductive layer 2202 of the plate 2204 in aconductive manner. Then, in response to the positive charges, negativecharges schematically appear on the electrode 800 d. Therefore, anelectrostatic attraction force is also generated between the electrode800 d and the corresponding portion of the plate 2204.

In this way, the electrostatic attraction is generated between the plate2204 and the electrodes 800 b and 800 d, for example.

The above-described steps in the generation of the electrostaticattraction actually proceed substantially in a simultaneous fashion inresponse to the voltage difference between the electrodes 800 b and 800d.

In addition, the dielectric layer 2201 and the conductive layer 2202 ofthe plate 2204, which are electrically floating, have a certain voltagedetermined between the voltages of the electrodes 800 b and 800 d.Accordingly, the voltage difference between this certain voltage and thevoltage of the electrode 800 b generates the. electrostatic attractionand also the voltage difference between the certain voltage and thevoltage of the electrode 800 d generates the electrostatic attraction.This certain voltage may vary mainly according to structural factorsincluding areas of the space 901 and the electrodes 800 b and 800 d, forexample. The thus-generated electrostatic attraction forces cause theplate 2204 to tilt towards the electrodes.

Referring to FIGS. 100A–100M, another light deflecting operation by thelight deflecting apparatus 2100 f is explained. FIG. 100A is a planeview of the light deflecting apparatus 2100 f with indications of crosssection lines. FIGS. 100B and 100C are cross-section views of the lightdeflecting apparatus 2100 f taken on line JJ—JJ and line KK—KK,respectively, of FIG. 10A. FIGS. 100D–100M explain operations of thelight deflecting apparatus 2100 f.

In the following discussion, the views of FIGS. 100D, 100F, 100H, and100J show the movements of the plate 2204 with a first axis taken online LL—LL, and the views of FIGS. 100E, 100G, 100I, and 100K show themovements of the plate 2204 with a second axis taken on line JJ—JJ. Inaddition, the view of FIG. 100L shows the movement of the plate 2204with a third axis taken on line PP—PP and the view of FIG. 100M showsthe movement of the plate 2204 with a fourth axis taken on line KK—KK.

FIGS. 100D and 100E show the initial status of the light deflectingapparatus 2100 f in a manner similar to FIGS. 98D and 98E. FIGS. 100Fand 100G show the reset operation which is similar to that shown inFIGS. 98F and 98G, except for the voltages applied to the electrodes 800a–800 d. The electrodes 800 a is applied with a voltage of Y volts. Theelectrodes 800 c and 800 d and the conductive layer 802 are applied witha voltage of Y/2 volts. The electrode 800 b is applied with a voltage of0 volts. BY the reset operation, the plate 2204 contacts the supportingmember 2103 and is applied with a voltage of Y/2 volts from theconductive layer 802 of the supporting member 2103.

The electrodes 800 c and 800 d are applied with the same voltage as theplate 2204, and there is no electrostatic attraction force generatedbetween the plate 2204 and the electrodes 800 c and 800 d. The voltagedifferences between the electrode 800 b and the plate 2204 and betweenthe plate 2204 and the electrode 800 a are both Y/2 volts, andrelatively strong electrostatic attraction forces are generatedtherebetween. Accordingly, the plate 2204 is tilted in the direction ofthe electrodes 800 a and 800 b. This status is referred to as the resetstatus.

The first operation for moving the plate 2204 with the first axis isshown in FIGS. 100H and 100I. In this operation, the electrode 800 c isapplied with a voltage of Y/2 volts, the electrodes 800 a and 800 b andthe conductive layer 802 are applied with a voltage of approximately Y/2volts, and the electrode 800 d is applied with a voltage of 0 volts.Under such conditions, the plate 2204 is quickly tilted in the oppositedirection relative to the reset direction and stops its movement whenthe portion 2204 d of the plate 2204 contacts the substrate 2101.

When the same bias voltages of either positive or negative are added tothe voltages of the electrodes and the conductive layer, no change iscaused in the movement of the plate. That is, the tilt direction of theplate 2204 can quickly be changed by applications of different voltagesto adjacent two electrodes and intermediate voltages to the remainingtwo electrodes and the conductive layer 802. The voltage of Y volts is apredetermined voltage and is determined such that a voltage of Y/2 voltsapplied to the conductive layer 802 is slightly greater than a voltageof Z volts which is a lowest value to cause the plate 2204 to tilt to adifferent position.

The second operation for moving the plate 2204 with the second axis isshown in FIGS. 100J and 100K. In this operation, the electrode 800 b isapplied with a voltage of Y volts, the electrodes 800 a and 800 c andthe conductive layer 802 are applied with a voltage of approximately Y/2volts, and the electrode 800 d is applied with a voltage of 0 volts.Under such conditions, the plate 2204 is quickly tilted with a differentaxis and stops its movement when the portion 2204 e of the plate 2204contacts the substrate 2101. Therefore, the plate 2204 can be tiltedwith different two axes by the first and second operations.

As for the action of the electrostatic attraction force, the case of theabove-described first operation, shown in FIGS. 100H and 100I, isexplained. When the conductive layer 802 is applied with a voltage ofapproximately Y/2 volts, the plate 2204 will have a voltage ofapproximately Y/2 volts. Accordingly, the portions of the plate 2204facing the electrodes 800 a and 800 b have substantially the samevoltages as the electrodes 800 a and 800 b and therefore noelectrostatic attraction force is generated. However, the portions ofthe plate 2204 facing the electrodes 800 c and 800 d have a voltagedifference of approximately Y/2 volts and therefore electrostaticattraction forces are caused in response to the voltage difference ofapproximately Y/2 volts. With such forces, the plate 2204 is moved tothe other position with the first axis.

In the second operation, shown in FIGS. 100J and 100K, the electrostaticattraction forces are generated in a manner similar to theabove-described first operation and, as a result, the plate 2204 ismoved to the other position with the second axis. In this example, theelectrodes applied with the largest voltage and the smallest voltage areneeded to be in the same side relative to the line of the movement axisfor the plate 2204 passing through the top portion of the plate 2204. Inthe case of four electrodes, adjacent two electrodes are needed to havethe largest and smallest voltages.

One of remarkable advantages of the light deflecting apparatus accordingto the present invention is explained below with reference to FIG. 100H.In FIG. 100H, the electrodes 800 c and 800 d are applied with voltagesof Y volts and 0 volts, respectively. Therefore, even if the plate 2204is disengaged from the supporting member 2103 and becomes in anelectrically-floating status during the tilting movement, theelectrostatic attraction force is generated to act on the plate 2204facing the electrodes 800 c and 800 d, as described in the explanationmade with reference to FIG. 99. Accordingly, the plate 2204 is changedto a desired position to perform the light reflection in a desireddirection. That is, one of the advantages of the light deflectingapparatus according to the present invention is that the lightdeflecting apparatus can stably perform the light deflection. Thisadvantage will be effective particularly when the light deflectingapparatus is used in an upside down orientation, in which the plate 2204is usually disengaged from the supporting member 2103 when no voltage isapplied to the light deflecting apparatus.

The light deflecting apparatus 2100 f performs a third operation tochange the axis of light deflection. The third operation is explainedwith reference to FIGS. 100L and 100M. In the third operation, theelectrode 800 a is applied with a voltage of X volts. The electrodes 800b and 800 c are applied with a voltage of X/2 volts. The electrode 800 dand the conductive layer 802 are applied with a voltage of 0 volts. Thevalue X is the one used in the description made with reference to FIGS.98A–98K.

A strong electrostatic attraction force is generated between a portionof the plate 2204 and the electrode 800 a, and acts on such portion ofthe plate 2204. A weak electrostatic attraction force is generatedbetween another portion of the plate 2204 and the electrodes 800 b and800 c, and acts on such another portion of the plate 2204. Noelectrostatic attraction force is generated between further anotherportion of the plate 2204 and the electrode 800 d, and therefore acts onsuch further another portion of the plate 2204. As a consequence, theplate 2204 is tilted in a direction towards the electrode 800 a, asshown in FIG. 100M. The plate 2204 ultimately contacts the substrate2101 by an edge portion 2204 f of the plate 2204 which is on an edge ofa diagonal line of the plate 2204. Thus, the light deflecting apparatus2100 f performs the light deflection with the third axis taken on lineKK—KK. Likewise, the light deflecting apparatus 2100 f can perform thelight deflection with the forth axis taken on line PP—PP by arbitrarilychanging the applications of voltages to the electrodes 800 a–800 d andthe conductive layer 802. With the third and fourth axes, it is possiblefor the light deflecting apparatus 2100 f to use four different tiltpositions.

Thus, the light deflecting apparatus 2100 f can perform the lightdeflection with eight different tilt positions with arbitrarilyapplications of voltages to the electrodes 800 a–800 d and theconductive layer 802. As described above, the voltage of X/2 voltsapplied to the electrodes 800 b and 800 c generates a weak electrostaticattraction force with the voltage of 0 volts applied to the plate 2204.Therefore, the plate 2204 may bend when it has a relatively smallstiffness. To avoid this problem, it is preferable to apply a smallervoltage or a voltage of 0 volts, the same voltage as applied to theconductive layer 802, to the electrodes 800 b and 800 c, or to apply novoltage to the electrodes 800 b and 800 c to make them in anelectrically floating status. When the electrodes 800 b and 800 c areapplied with the voltage of X/2 volts or are made in an electricallyfloating status, the tilt position of the plate 2204 can easily bechanged in an opposite direction towards the electrode 800 d simply bychanging the voltage applied to the conductive layer 802 from 0 volts toX volts.

It should be understood from the above-described various examples thatthe basic principle to tilt the normal to the light reflecting surfaceof the plate 2204 to a specific side is to apply a voltage to anelectrode in the specific side such that a difference in voltage betweenthe electrode in the specific side and the plate 2204 becomes maximum.The plate 2204 can be tilted towards a side by an application of avoltage between the plate 2204 and adjacent two electrodes and towardsan edge on a diagonal line by an application of a voltage between theplate 2204 and one electrode.

Referring to FIG. 101, a light deflecting apparatus 2100 g according toanother preferred embodiment of the present invention is explained. FIG.101 shows the light deflecting apparatus 2100 g modified on a basis ofthe light deflecting apparatus 2100 b of FIG. 93A. The substrate 2101,the supporting member 2103, and the plate 2104 are modified to asubstrate 2101 g, a supporting member 2103 g, and a plate 2104 g, whichare in a circular form. Accordingly, the angle brackets 2102 aremodified to angle brackets 2102 g and the electrodes 2301 are modifiedto eight electrodes 800 a–800 h, for example.

In the light deflecting apparatus 2100 g, the electrode 800 a is appliedwith a voltage of X volts, the electrode 800 e is applied with a voltageof 0 volts, and other electrodes are remained in an electricallyfloating status, for example. Then, the conductive layer 802 of thesupporting member 2103 g is applied with a voltage of 0 volts.Consequently, the plate 2104 g is tilted to the electrode 800 a due to alarge voltage difference between the plate 2104 g and the electrode 800a. If the conductive layer 802 is alternatively applied with a voltageof X volts, the plate 2104 g is tilted in an opposite direction towardsthe electrode 800 e. In this way, the plate 2104 g can be tilted inevery direction where an electrode presents by applications of voltagecombinations relative to the electrodes and the conductive layer of thesupporting member. Accordingly, the direction of the light reflectioncan selectively be determined among from eight directions.

In this embodiment, the supporting member 2103 g having a conical shapemay have another shape such as an octagonal pyramid, for example, sothat the octagonal shape of the supporting member corresponds to theshapes of the electrodes 800 a–800 h. With this structure, the plate2104 g can stay in each of the eight tilt positions in a more stablemanner.

When the number of the electrodes is six or more, the electrodes appliedwith the largest and smallest voltages are unnecessarily adjacent andallow a presence of one or more other electrodes therebetween. Anelectrode can be inserted between the electrodes with the largest andsmallest voltages in a case of six electrodes. However, in a case ofeight electrodes, up to two electrodes can be inserted between theelectrodes with the largest and smallest voltages. When one or moredifferent electrodes are inserted between the electrodes with thelargest and smallest voltages, the plate is tilted in a directiontowards a region between the two electrodes with the largest andsmallest voltages due to the relationship of the electrostaticattraction forces. When the number of the electrodes inserted betweenthe electrodes with the largest and smallest voltages is odd, such asone or three, the plate stably stays on the electrode inserted betweenthe electrodes with the largest and smallest voltages. It is thereforepreferable to apply no voltage to the inserted electrode and to make itin an electrically floating status so as to prevent a short circuit or adischarge between the larges and smallest voltages.

Next, a light deflecting array apparatus 1200 is explained withreference to FIGS. 102A and 102B. FIG. 102A is a plane view of the lightdeflecting array apparatus 1200, and FIG. 102B is a cross-section viewof the light deflecting array apparatus 1200 taken on line QQ—QQ of FIG.102A. The light deflecting array apparatus 1200 includes three pieces ofthe light deflecting apparatuses 2100 f of FIG. 98A, for example, whichare arranged in a one-dimension direction. The light deflecting arrayapparatus 1200 may include a number of the light deflecting apparatuses2100 f larger than three, and the light deflecting apparatuses 2100 fcan be arranged in two-dimension directions. With the light deflectingapparatus 1200 having a large number of integrated light deflectingapparatuses 2100 f, for example, it becomes possible to control a highprecision light deflection by driving them simultaneously andindependently. Each of the integrated light deflecting apparatuses 2100f may be referred to as an element.

In the light deflecting array apparatus 1200, a space around the plate2204 in each of the light deflecting apparatus 2100 f is in a nearvacuum. Such near vacuum in the light deflecting apparatus 2100 f can beproduced by conducting a vacuum sealing when the light-deflectingapparatus 2100 f is packaged.

In FIG. 102B, a manner in that the plates 2204 of the light deflectingarray apparatus 1200 are surrounded in the atmosphere is schematicallyexpressed. In a first element arranged in the leftmost position, theplate 2204 is tilted and the air under the plate 2204 is pressed. Thispressed air produces a buoyant force which acts on the plate 2204 of asecond element arranged in the middle position. The movement of theplate 2204 which is moving in a direction indicated by a white arrow isdisturbed by the buoyant force produced by the first element. Thisproblem is avoided by making the space around the plate 2204 in the nearvacuum.

When the plate 2204 is tilted at a high speed, the atmospheric airgenerally becomes a viscous drag which produces a slight delay inresponse. In a single device of the light deflecting array apparatus1200, this viscous drag can be reduced by a package for covering theentire apparatus to keep dust out.

In addition, the near vacuum of space around the plate 2204 may befilled with an inert gas such as a nitrogen gas, an argon gas, a heliumgas, a neon gas, and so forth. Amongst, the nitrogen gas is relativelyinexpensive and safe and is therefore preferable. An inert gas can beenclosed in the space around the plate 2204 by conducting the packagingof the light deflecting array apparatus 1200 in the same inert gas. Withthe inert gas enclosed in the space around the plate 2204, the moisturecontent in the space is reduced so that the contacting portion of theplate 2204 is prevented from fixing to the substrate 2101. However, ifthere is a concern that the enclosed gas produces a viscous drag inresponse to the movement of the plate 2204, the pressure of the gas ispreferably reduced before being enclosed.

Next, an image projection display apparatus 1300 using the lightdeflecting array apparatus 1200 is explained with reference to FIG. 103.FIG. 103 shows the image projection display apparatus 1300 whichprojects an image by deflecting light of an image with the lightdeflecting array apparatus 1200. The image projection display apparatus1300 includes a light switching mechanism 1301 and a projection screen1310. The light switching mechanism 1301 includes the light deflectingarray apparatus 1200, a light source 1302, a projection lens 1303, anaperture 1304, a rotary color hole 1305, and a micro-lens array 1306.

In the light switching mechanism 1301, the light source 102 emits lightW3 which travels, through the rotary color hole 1305 for a color displayand the micro-lens array 1306 for a high precision, to the lightdeflecting array apparatus 1200. The light W3 is reflected by the plates2204 of the elements of the light deflecting array apparatus 1200. Theplates 2204 are independently driven in accordance with input imagedata. That is, each of the plates 2204 changes its position according tothe input image data and, as a result, the reflection angle relative tothe input light W3 is changed according to the input image data.Therefore, the reflection of the light W3 is controlled according to theinput image data by the light deflecting array apparatus 1200. The lightW3 reflected by the light deflecting array apparatus 1200 travelsthrough the projection lens 1303 and the aperture 1304 to the screen1310 to form an image. Thus, the image projection display apparatus 1300including the light deflecting array apparatus 1200 effectively projectsa desired image on the screen.

In the image projection display apparatus 1300, the light deflectingarray apparatus 1200 is arranged at a position such that the normal toeach of the light reflecting surfaces of the plates 2204 is in adirection substantially equal to a direction of gravity when the plates2204 are in their initial status. With this arrangement, the gravityacts on the plate 2204 in contact with the supporting member 2103 andevenly acts on the plate 2204 without deviation even when the plate 2204is tilted in any direction. Therefore, the plate 2204 can stably betilted for a usage over an extended period of time. Since the plate 2204in this embodiment has no edge fixed to the substrate 2101, theabove-described effect by gravity is generated to a great extent. FIG.103 merely indicates a general structure of the image projection displayapparatus and, therefore, there is no indication in FIG. 103 for adirection of the plate 2204 in the initial status. When the arrangementof the plate 2204 in the initial status relative to the gravity isapplied, mirrors may effectively be used intermediately on an as neededbasis.

Next, an image forming apparatus 1400 using the light deflecting arrayapparatus 1200 is explained with reference to FIG. 104. FIG. 104 showsthe image forming apparatus 1400 which forms an image by opticallywriting image data with an electrophotographic method using the lightdeflecting array apparatus 1200. The image forming apparatus 1400includes an image carrying mechanism 1401, a latent image formingmechanism 1402, a development mechanism 1403, a transfer mechanism 1404,a charging mechanism 1405, a fixing mechanism 1406, a sheet ejectingtray 1407, and a cleaning mechanism 1408. The latent image formingmechanism 1402 includes the light deflecting array apparatus 1200, alight source 1402 a, a first lens system 1402 b, and a second lenssystem 1402 c.

The image carrying mechanism 1401 includes a drum-shaped photosensitivesurface and is rotated in a direction C9. The image carrying mechanism1401 is evenly charged by the charging mechanism 1405. The latent imageforming mechanism 1402 forms a latent image on the photosensitivesurface of the image carrying mechanism 1401. At this time, the elementsof the light deflecting array apparatus 1200 are switched in accordancewith the input image data so as to form the latent image. Thedevelopment mechanism 1403 develops with toner the latent image formedon the photosensitive surface of the image carrying mechanism 1401. Thetransfer mechanism 1404 transfers the toner image onto a recording sheetV. The fixing mechanism 1406 fixes the toner image to the recordingsheet V with heat and pressure. The recording sheet V is ejected to thesheet ejecting tray 1407. The cleaning mechanism 1408 cleans off thephotosensitive surface of the image carrying mechanism 1401.

In the latent image forming mechanism 1402, light W4 emitted from thelight source 1402 a travels through the first lens system 1403 to thelight deflecting array apparatus 1200. The elements of the lightdeflecting array apparatus 12000 are independently and simultaneouslydriven in accordance with input image data. That is, every reflectionangles relative to the input light W4 are changed according to the inputimage data. Therefore, the reflection of the light W4 towards thephotosensitive surface of the image carrying member 1401 is controlledaccording to the input image data by the light deflecting arrayapparatus 1200. The light W4 reflected by the light deflecting arrayapparatus 1200 travels through the second lens system 1404 to thephotosensitive surface to form a latent image. Thus, the image formingapparatus 1400 including the light deflecting array apparatus 1200effectively forms an image according to the input image data.

Next, an optical data transmission apparatus 1500 using the lightdeflecting array apparatus 1200 is explained with reference to FIG.105A. FIG. 105A shows the optical data transmission apparatus 1500 fortransmitting an optical data signal. The optical data transmissionapparatus 1500.includes an optical data input mechanism 1502, a firstoptical deflecting array 1503, a first control mechanism. 1504, a secondoptical deflecting array 1505, a second control mechanism 1506, anoptical data output mechanism 1507, and a plurality of signaltransmission ports 1508.

An optical data signal is transmitted to the optical data transmissionapparatus 1500 from the optical data input mechanism 1502 which includesa plurality of signal transmission ports 1508. In the optical datatransmission apparatus 1500, the optical data signal is deflected intwo-dimension directions by the first and second optical deflectingarrays 1503 and 1505 and is output from the selected output ports of theoptical data output mechanism 1507 which includes a plurality of signaltransmission ports 1508. In this embodiment, the two stages of the firstand second optical deflecting arrays 1503 and 1505 are preferablyprovided to achieve a relatively wide deflecting angle. However, asingle optical deflecting array may also be suitable depending upon anumber of the selected ports. The elements included in the opticaldeflecting arrays 1503 and 1505 are driven by the control mechanisms1504 and 1506, respectively, in an independent and simultaneous manner.

Although the optical data input mechanism and the optical data outputmechanism are separated in the above discussion for the conveniencesake, it should be noted that input and output mechanisms in the opticaldata transmission are generally in common since optical data isbi-directionally transmittable.

FIG. 105B shows an optical data transmission apparatus 1510 using asingle unit of the light deflecting apparatus 2100 f, for example. Theoptical data transmission apparatus 1510 includes an input/output port1511, the light deflecting apparatus 2100 f, and a signal input/outputmechanism 1513. The signal input/output mechanism includes fourinput/output ports 1514, for example. Since the light deflectingapparatus 2100 f can select four light deflection directions, asdescribed above, it is possible to provide a single input/output port atone end and four input/output ports at the other end. In FIG. 105B, alight path shown with a solid line indicates a case when theinput/output port 1514 is selected by the light deflecting apparatus2100 f, and a light path shown with a dotted-line indicates a case whenthe light deflecting apparatus 2100 f switches to another input/outputport.

Reference numeral 1512 denotes a mirror which reflects the light fromthe input/output port 1511 to the light deflecting apparatus 2100 f. Asan alternative to this, it is possible to eliminate the mirror 1512 andto arrange the input/output port 1511 at the center of the signalinput/output mechanism 1513, by which the manufacturing cost can bereduced. In addition, it is possible to integrate plural sets of theabove-described input/output ports into a single unit.

Referring to FIGS. 106A–106H, an exemplary method of making a lightdeflecting apparatus is explained. In this discussion, a lightdeflecting apparatus to be made is an apparatus similar to the lightdeflecting apparatus 2100 f of FIG. 98A, as an example. Each of theviews shown in FIGS. 106A–106H is a cross section view taken on lineKK—KK of FIG. 98A. In this method, a plurality of sections are formed ona silicon substrate. The plurality of sections are arranged in either aone-dimension direction or two-dimension directions. To make a pluralityof single units of the light deflecting apparatus 2100 f, it ispreferable to provide a margin for separation between the sections.However, the sections are needed to be formed as close as possible tomake an array of the light deflecting apparatuses 2100 f.

A first process (see FIG. 106A) provides a silicon oxide film 1601,which forms the dielectric layer 801 of the supporting member 2103, onthe silicon substrate 2101 with the plasma CVD method. Then, aphotography using a photomask having a pattern with an area coveragemodulation or a photography which thermally deforms a resist pattern isused to form a resist pattern having an approximate shape and athickness of the supporting member 2103. After that, the formed resistpattern is deformed to an exact shape of the dielectric layer 801 withthe dry etching method.

A subsequent process (see FIG. 106B) provides the electrodes 800 b, 800d, and the conductive layer 801 made of a titanium nitride thin film.The electrodes 800 a and 800 c which are not shown in FIG. 106B are alsoformed at the same time in this process. In this process, the titaniumnitride thin film is formed with the DC magnetron sputtering processwith a target of titanium, and is patterned into the electrodes 800a–800 d using the photography and the dry etching method.

The next process (see FIG. 106C) forms a noncrystalline silicon filmwith the sputtering method, and the noncrystalline silicon film issmoothed through the process time control using the CMP technology. Theremaining noncrystalline silicon film is referred to as a firstsacrifice layer 1602. As an alternative to the noncrystalline siliconfilm, the first sacrifice layer 1602 may be made of a polyimide film ora photosensitive organic film (i.e., a resist film generally used in asemiconductor process), or a polycrystalline silicon film. The smoothingmethod may be the reflow method with the thermal processing or the etchback method with the dry etching.

The next process (see FIG. 106D) forms a silicon nitride layer as thedielectric layer 2201 of the plate 2204 with the plasma CVD method.Then, the silicon nitride layer is patterned into the opening 2203 andthe dielectric layer 2201 using the photography and the dry etchingmethod. Subsequently, an aluminum metal film constituting the lightreflecting region combined with the conductive layer 2202 is formed withthe sputtering method. After that, the aluminum metal film is patternedwith the photography and the dry etching method.

The next process (see FIG. 106E) forms a noncrystalline silicon filmwith the sputtering method. This noncrystalline silicon film is referredto as a second sacrifice layer 1603. As an alternative to thenoncrystalline silicon film, the second sacrifice layer 1603 may be madeof a polyimide film or a photosensitive organic film (i.e., a resistfilm generally used in a semiconductor process), or a polycrystallinesilicon film. The second sacrifice layer 1603 is preferably made of thesame material as the first sacrifice layer 1602.

The subsequent process (see FIG. 106F) divides each light deflectingapparatus with patterns of the first and second sacrifice layers 1602and 1603 together using the photography and the dry etching method. Atthis time, the pattern areas of the first and second sacrifice layers1602 and 1603 are slightly larger than the area of the plate 2204. Thisprocess prepares for the next process for providing the angle brackets2102 c.

The next process (see FIG. 106G) forms a silicon oxide film constitutingthe angle brackets 2102 c with the plasma CVD method. Then, the siliconoxide film is patterned to make the angle brackets 2102 c with thephotography and the dry etching method.

The next process (see FIG. 106H) removes the remaining first and secondsacrifice layers 1602 and 1603 through an opening with a wet etchingmethod using a TMAH (tetra-methyl-ammonium-hydroxide) liquid so that theplate 2204 is supported by the supporting member 2103 for a freemovement within the predetermined space. Thus, the procedure for makingthe light deflecting apparatus 2100 f shown in FIG. 98A is completed.

Referring to FIGS. 107A–107I, another exemplary method of making a lightdeflecting apparatus is explained. In this discussion, a lightdeflecting apparatus to be made is an apparatus similar to the lightdeflecting apparatus 2100 e of FIG. 97A, as an example. Each of theviews shown in FIGS. 107A–107I is a cross section view taken on lineII—II of FIG. 97A. This method is a part of the manufacturing procedurefor manufacturing the light deflecting apparatus 2100 e, including atleast processes of forming a dielectric thin film on a plurality ofelectrodes and patterning the dielectric thin film to form projections.

A first process (see FIG. 107A) provides a silicon oxide film, whichforms the supporting member 601, on the silicon substrate 2101 with theplasma CVD method. Then, a photography using a photomask having apattern with an area coverage modulation or a photography whichthermally deforms a resist pattern is used to form a resist patternhaving an approximate shape and a thickness of the supporting member601. After that, the formed resist pattern is deformed to an exact shapeof the supporting member 601 with the dry etching method.

The next process (see FIG. 107B) forms the electrodes 2301 and theconductive top portion 602 made of a titanium nitride thin film. In thisprocess, the titanium nitride thin film is formed with the DC magnetronsputtering process with a target of titanium, and is patterned into theelectrodes 2301 using the photography and the dry etching method.

The next process (see FIG. 107C) forms a silicon nitride film serving asthe insulating film 603 for protecting a short circuit between the plate2104 and the electrodes 2301 with the plasma CVD method. After that, thesilicon nitride film is patterned into the projections 701 in a desiredshape at predetermined positions using the photography and the dryetching method. At this time, an opening is provided near the conductivetop portion 602 for applying a voltage to the plate 2104.

The next process (see FIG. 108D) forms a noncrystalline silicon filmwith the sputtering method, and the noncrystalline silicon film issmoothed through the process time control using the CMP technology. Theremaining noncrystalline silicon film is referred to as a firstsacrifice layer 1702. As an alternative to the noncrystalline siliconfilm, the first sacrifice layer 1702 may be made of a polyimide film ora photosensitive organic film (i.e., a resist film generally used in asemiconductor process), or a polycrystalline silicon film. The smoothingmethod may be the reflow method with the thermal processing or the etchback method with the dry etching.

The next process (see FIG. 107E) forms the plate 2104 made of analuminum metal film having conductivity to combine with the lightreflecting region with the sputtering method. After that, the aluminummetal film is patterned with the photography and the dry etching method.

The next process (see FIG. 107F) forms a noncrystalline silicon filmwith the sputtering method. This noncrystalline silicon film is referredto as a second sacrifice layer 1703. As an alternative to thenoncrystalline silicon film, the second sacrifice layer 1703 may be madeof a polyimide film or a photosensitive organic film (i.e., a resistfilm generally used in a semiconductor process), or a polycrystallinesilicon film. The second sacrifice layer 1703 is preferably made of thesame material as the first sacrifice layer 1702.

The subsequent process (see FIG. 107G) divides each light deflectingapparatus with patterns of the first and second sacrifice layers 1702and 1703 together using the photography and the dry etching method. Atthis time, the pattern areas of the first and second sacrifice layers1702 and 1703 are slightly larger than the area of the plate 2104. Thisprocess prepares for the next process for providing the angle brackets2102 c.

The next process (see FIG. 107H) forms a silicon oxide film constitutingangle brackets 2102 c with the plasma CVD method. Then, the siliconoxide film is patterned to make the angle brackets 2102 c with thephotography and the dry etching method.

The next process (see FIG. 107I) removes the remaining first and secondsacrifice layers 1702 and 1703 through an opening with a wet etchingmethod using a TMAH (tetra-methyl-ammonium-hydroxide) liquid so that theplate 2104 is supported by the supporting member 601 for a free movementwithin the predetermined space. Thus, the procedure for making the lightdeflecting apparatus 2100 e shown in FIG. 97A is completed.

Referring to FIGS. 108A–108D and 109A–109C, various shapes of thesupporting member is explained. FIG. 108A shows the supporting member2103 in a basic conical shape having a top portion 2103 a which may beneeded to be strengthen to support the plate 2104 which is acted by theelectrostatic attraction force. To provide a high mechanical strength tothe top portion 2103 a, the top portion 2103 a may be rounded, as shownin FIG. 108B. FIG. 108C shows a preferable shape of the supportingmember 2103 which combines a frustum of a cone and a circular cylinderand provides a wider apex angle to the top portion 2103 a in comparisonwith the supporting members 2103 having the conical shape with the sameheight. The top portion 2103 a of FIG. 108C may also be rounded, asshown in FIG. 108D.

It is also possible to provide a flat apex to the top portion 2103 a, asshown in FIGS. 109A–109C. With these flat apexes, a concern of a stressconcentration is eliminated. A shape combining a frustum of a cone and acircular cylinder, as shown in FIG. 109B, is also preferable. When thearea of the top portion 2103 a is relatively small, the circularcylinder, as shown in FIG. 109C, may also be used.

Referring to FIGS. 110A and 110B, a light deflecting apparatus 2100 haccording to another preferred embodiment of the present invention isexplained. FIG. 110A is a plane view of the light deflecting apparatus2100 h, and FIG. 110B is a cross-section view of the light deflectingapparatus 2100 h taken on line QQ—QQ of FIG. 110A. The light deflectingapparatus 2100 h of FIG. 110A is an apparatus modified on the basis ofthe light deflecting apparatus 2100 e of FIG. 97A, that is, theprojections 701 are modified to projections 2005. The projections 2005have a strip shape different from the projections 701, although they canbe formed by a method similar to that used for the projections 701 andhave a function similar to that of the projections 701.

The projections 2005 are made of an insulation film and are placed onthe four electrodes 2301 in a form of a plurality of strip shapes. Awidth and a length of each strip and a pitch of the strips arearbitrarily determined according to a relationship between theelectrostatic attraction force and the stiffness of the plate 2104within a limit that the plate 2104 does not touch the electrodes 2301when being elastically deformed. The roof-like-shaped slopes of thesupporting member 601 may be in a polygonal shape similar to that shownin FIG. 101.

Since the size of the projections 2005 is near a limit of resolution inpreparation of a photomask for forming the shape of the projections2005, the projections 701 only in the circular shape, as shown in FIG.97A, may be produced with a degraded machining accuracy. Thestrop-shaped projections, as shown in FIG. 110A, have a larger area andincrease the machining accuracy.

Referring to FIGS. 111A and 111B, a light deflecting apparatus 2100 iaccording to another preferred embodiment of the present invention isexplained. FIG. 111A is a plane view of the light deflecting apparatus2100 i, and FIG. 111B is a cross-section view of the light deflectingapparatus 2100 i taken on line RR—RR of FIG. 111A. The light deflectingapparatus 2100 i of FIG. 111A is an apparatus modified on the basis ofthe light deflecting apparatus 2100 h of FIG. 110A, that is, theprojections 2005 are modified to projections 2105. The projections 2105are formed in a method partly different from the method used for theprojections 701 but are similar to the projections 2005 in otheraspects. The projections 2105 are not placed on the electrodes 2301 butare projected between the electrodes.

The projections 2105 are formed with a predetermined pattern when thesupporting member 601 is formed and before the four electrodes 2301 areformed. When the supporting member 601 is made of an insulatingmaterial, it is sufficient to pattern the surface of the supportingmember 601 itself. However, when the supporting member 601 is made of aconductive material, the insulative projections 2105 are formed with apredetermined pattern after an insulating film is formed on the surfaceof the supporting member 601. The electrodes 2301 are formed in flatsurfaces provided around the projections 2105. In addition, it is neededto form a conductive member 602 on the top portion of the supportingmember 601 for applying a voltage to the plate 2104. This conductivemember 602 can be formed together when the electrodes 2301 are formed.The reason of forming the electrodes 2301 out of the projections 2105 isthat, when the electrodes are arranged under the projections,electrostatic charges are generated on the projection surfaces due topolarization and attract the plate 2104. When such attraction of theplate 2104 by the electrostatic charges is greater, a fixing phenomenonmay occur in which the plate 2104 is kept attracted to the projectionseven after the voltages applied to the electrodes are out.

Referring to FIG. 112, a light deflecting array apparatus 1200 a isexplained. As shown in FIG. 112, the light deflecting array apparatus1200 a includes a plurality of the light deflecting apparatuses 2100 gof FIG. 101 arranged in a closest-packed structure and in atwo-dimension array form. For this arrangement, the angle brackets aremodified. The view shows only a minimum portion of the array structurebut an actual array will have an extended structure in two-dimensiondirections.

In FIG. 112, reference numeral 2102 h denotes joint angle brackets whichhave functions of stopping the plate 2104 as the angle brackets andjointing two light deflecting apparatuses. Each of the joint anglebrackets 2102 h is shared by two light deflecting apparatuses 2100 g. Ingeneral, when equal-sized small circles are arranged in asmallest-packed structure, as shown in FIG. 112, each circle issurrounded in contact by six circles making contact in a regular mannerbetween adjacent two among the six circles. Accordingly, six joint anglebrackets 2102 h are needed to joint the light deflecting apparatus 2100g at the center to the six surrounding light deflecting apparatus 2100g. In integration of a plurality of the light deflecting apparatus 2100g to make the light deflecting array apparatus 1200 a, for example, itis possible to form the substrate 2101 g and the joint angle brackets2102 h in one piece.

To make a one-direction light deflecting array apparatus (not shown)using the light deflecting apparatuses 2100 g, it may also be possibleto integrate the substrate 2101 and the joint angle brackets 2102 h inone piece. In this case, the number of the joint angle brackets 2102 hmay be four, as shown in FIG. 101.

In addition, when the plurality of the light deflecting apparatuses 2100g are arranged in a square matrix form, not in a closest-packedstructure, the number of the joint angle brackets 2102 h may suitably befour.

Referring to FIGS. 113A, 113B and 114, the angle brackets 2102 inmodified shapes are explained. FIG. 113A shows an edge angle bracket3102 having an angled top portion 3102 a, a vertical portion 3102 b, andan extended base portion 3102 c. The angled top portion 3102 a and theextended base portion 3102 c are projected in opposite directionsrelative to the vertical portion 3102 b. This edge angle bracket 3102 isused in the light deflecting apparatuses such as those shown in FIGS. 91and 101, for example, in which the angle brackets are arranged at eachside or circumferential edge, not at the corners. As understood from aview of FIG. 114, the space reserved for the tilt movement of the plate2104 is limited to a space smaller than the substrate 2101 by thepresence of the extended base 3102 c. This is a result of increasing themechanical strength of the angle brackets, since the angle brackets areprone to be broken even by a relatively small stress if they are joinedto the substrate 2101 with too small areas.

FIG. 113B shows a corner angle bracket 4102 having an angled top portion4102 a, a vertical portion 4102 b, and an extended base portion 4102 c.This corner angle bracket 4102 is used in the light deflectingapparatuses such as those shown in FIG. 94, for example, in which theangle brackets are arranged at each corner of the substrate 2101. A wayfor using such corner angle bracket 4102 and its effect are more or lesssimilar to those of the edge angle bracket 3102.

Referring to FIGS. 115A, 115B, 116, and 117, the joint angle brackets2102 h in different shapes are explained. FIG. 115A shows anU-like-shaped joint angle bracket 5102 which is an angle bracket sharedby two light deflecting apparatuses in a way as shown in FIG. 112. TheU-like-shaped joint angle bracket 5102 has a shape such that two edgeangle brackets 3102 are connected. More specifically, a flat-formed base5102 c is equally placed on a connecting line K of connected twosubstrates 2101, disposing vertical portions 5102 b on edges of theflat-formed base 5102 c facing each other and stopper portions 5102 a onthe vertical portions 5102 b to project in directions respectivelyopposite to the connecting line K.

FIG. 116 shows a manner in which the U-like-shaped joint angle bracket5102 is used.

FIG. 115B shows a T-like-shaped joint angle bracket 6102 which is madeby connecting two angle brackets 2102 shown in FIG. 91. TheT-like-shaped joint angle bracket 6102 has a flat top portion 6102 a anda vertical portion 6102 b. The width of the vertical portion 6102 b isat least twice of the width of the vertical portion 5102 b so that thevertical portion 6102 b is directly connected to the substrate 2101 witha sufficiently large area to have a relatively high mechanical strength.

Referring to FIGS. 118–127, an exemplary method of making a lightdeflecting apparatus is explained. In this discussion, a lightdeflecting apparatus to be made is referred to as a light deflectingapparatus 2100 j. The light deflecting apparatus 2100 j is similar tothe light deflecting apparatus 2100 f of FIG. 98A, except for therelatively small convex portion 2204 a provided to the central positionof the plate 2204 in contact with the supporting member 2103. With thisconvex portion 2204 a, the plate 2204 stably tilts with a self-centeringeffect.

A first process (see FIG. 118) provides the supporting member 2103. Asilicon oxide film constituting the supporting member 2103 is formed onthe silicon substrate 2101 with the plasma CVD method. Then, thephotography using a photomask having a pattern with an area coveragemodulation or the photography which thermally deforms a resist patternis used to form a resist pattern having an approximate shape and athickness of the supporting member 2103. After that, the formed resistpattern is deformed to an exact shape of the supporting member 2103 withthe dry etching method.

In the above process, the silicon oxide film having a thickness ofapproximately 2 μm may be formed, and the works for forming thesupporting member 2103 may be performed in an upper layer ofapproximately 1 μm.

The height of the top of the supporting member 2103 is approximately 1μm.

The next process (see FIG. 119) provides the electrodes 2301. In thisprocess, the electrodes 2301 are made of a titanium nitride (TiN) film.A titanium nitride film is formed to have a thickness of 0.01 μm withthe DC magnetron sputtering process and is patterned into the electrodes2301 with the photography and the dry etching method.

The next process (see FIG. 120) provides a protection layer 2301 a onthe electrode 2301. The protection layer 2301 a is made of a siliconnitride film having a thickness of 0.2 μm with the plasma CVD method.

The next process (see FIG. 121) provides a first sacrifice layer 2802. Anoncrystalline silicon film having a thickness of 2 μm is formed on theprotection layer 2301 a with the sputtering method, and thenoncrystalline silicon film is smoothed through a process time controlusing the CMP. In this example, the process time control is conductedwith reference to a time period in that the thickness of thenoncrystalline silicon film on the top of the supporting member 2103 iscompletely removed and the supporting member 2103 is exposed outside. Inaddition, the CMP is set to conditions in that the supporting member2103 and the protection layer 2301 a are more polished so that, aroundthe top portion of the supporting member 2103, a supporting point 2103 aof the supporting member 2103 remains and the noncrystalline siliconfilm thinly remains. The supporting point of the supporting member 2103is projected by approximately 0.2 μm. The noncrystalline silicon filmremaining on the protection layer 2301 a is referred to as the firstsacrifice layer 2802.

As an alternative to the noncrystalline silicon film, the firstsacrifice layer 2802 may be made of a polyimide film or a photosensitiveorganic film, or a resist film or a polycrystalline silicon film whichare generally used in a semiconductor process. The smoothing method maybe the etch back method with the dry etching.

The next process (see FIG. 122) provides a second sacrifice layer 2803.A noncrystalline silicon film of a 0.1-μm thick is formed on the firstsacrifice layer 2802 to cover the top portion of the supporting member2103 with the sputtering method.

The next process (see FIG. 123) provides the dielectric and conductivelayers 2201 and 2202, respectively. A 0.2-μm-thick silicon nitride filmconstituting the dielectric layer 2201 is formed on the first sacrificelayer 2802 with the plasma CVD method and subsequently a 0.05-μm-thickaluminum metal film is formed on the silicon nitride layer with thesputtering method. After that, the aluminum metal film and the siliconnitride layer are patterned with the photography and the dry etchingmethod, respectively. The dielectric layer 2201 is formed in a shapeslightly smaller than the substrate 2101 to leave a sufficient space toform the angle brackets 2102 c in the later process. Further, theconductive layer 2202 is formed in a shape slightly smaller than thedielectric layer 2201 so as to be placed on the dielectric layer 2201.

The next process (see FIG. 124) provides a third sacrifice layer 2804. A1-μm-thick noncrystalline silicon film is formed with the sputteringmethod. This noncrystalline silicon film is referred to as a secondsacrifice layer 2804. The third sacrifice layer 2804 may made of apolyimide film or a photosensitive organic film, or a resist film orpolycrystalline silicon film which are generally used in a semiconductorprocess.

The next process (see FIG. 125) provides a space for forming the anglebrackets 2102 c. The first, second, and third sacrifice layers 2802,2803, and 2804 are patterned together at the same time using thephotography and the dry etching method. As a result of this patterning,a portion around the circumference of the substrate 2101 is removed anda space for the angle brackets 2102 c is formed. At this time, the areasof the remaining first, second, and third sacrifice layers 2802, 2803,and 2804 are slightly larger than the area of dielectric layer 2201 sothat the dielectric layer 2201 is not exposed.

The next process (see FIG. 126) provides the angle brackets 2102 c. A0.8-μm-thick silicon oxide film is formed with the plasma CVD method andis patterned with the photography and the dry etching method, therebymaking the angle brackets 2102 c. The shape of the angle bracket is notlimited to that of the angle bracket 2102 c but may be those shown inFIGS. 113A, 113B, 115A, and 115B.

The final process (see FIG. 127) removes the remaining first, second,and third sacrifice layers 2802, 2803, and 2804 through an opening withthe wet etching method so that the plate 2204 having the lightreflecting region is supported by the supporting member 2103 for a freemovement within the space determined by the substrate 2101, the anglebrackets 2102 c, and the supporting member 2103. Thus, the procedure formaking the light deflecting apparatus 2100 j is completed.

With this method, the convex portion 2204 a at the center in thebackside of the plate 2204 is engaged with the top portion of thesupporting member 2103, so that the plate 2204 is not apt to slide fromthe top portion of the supporting member 2103 when being tilted by theaction of the electrostatic attraction force. Therefore, the plate 2204is always stably supported by the supporting member 2103. Accordingly,the direction control for the light deflection in the use of the lightdeflecting apparatus 2100 j made with this method for a micro mirrordevice, for example, can be conducted in a high precision manner.

Numerous additional modifications and variations are possible in lightof the above teachings. It is therefore to be understood that within thescope of the appended claims, the disclosure of this patentspecification may be practiced otherwise than as specifically describedherein.

1. A method of deflecting input light in directions for at least onedeflection-axis, comprising the steps of: providing a substrate; forminga supporting member on a surface of said substrate; forming a pluralityof electrodes on said surface of said substrate corresponding to saiddirections for at least one deflection-axis; forming a plate memberincluding light reflecting means disposed on a surface of said platemember for reflecting input light; placing said plate member on saidsupporting member so that another surface of said plate member oppositeto said surface having said light reflecting means faces said pluralityof electrodes; forming space regulating members on edges of said surfaceof said substrate for regulating a space in which said plate memberplaced on said supporting member is freely movable; and applyingpredetermined voltages to said plurality of electrodes to change a tiltof the plate member in accordance with said voltages applied so as todeflect the input light in a direction out of said directions for atleast one deflection-axis.
 2. A method as defined in claim 1, whereinsaid predetermined voltages include at least one different voltage.
 3. Amethod as defined in claim 1, wherein in said forming step of formingsaid supporting member, said supporting member is formed on said surfaceof said substrate such that a center of gravity of said supportingmember is on a normal to a center of said surface of said substrate. 4.A method as defined in claim 1, wherein in said forming step of formingsaid supporting member, said supporting member is formed to have atleast one slope connecting between a top portion and a bottom edge ofsaid supporting member.
 5. A method as defined in claim 4, wherein whensaid applying step applies said predetermined voltages to said pluralityof electrodes, the plate-like-shaped thin film member tilts inaccordance with said voltages applied to come in contact with said atleast one slope of said supporting member so as to deflect the inputlight in said arbitrary direction out of said directions for at leastone deflection-axis.